scholarly journals A large majority of awake hippocampal sharp-wave ripples feature spatial trajectories with momentum

2021 ◽  
Author(s):  
Emma L Krause ◽  
Jan Drugowitsch
Keyword(s):  
Temporal Dynamics ◽  
Probabilistic Approach ◽  
Complete Characterization ◽  
Sharp Wave ◽  
Natural Movement ◽  
Spatio Temporal ◽  
Almost All ◽  
Spatial Trajectories

During periods of rest, hippocampal place cells feature bursts of activity called sharp-wave ripples (SWRs). Heuristic approaches to their analysis have revealed that a small fraction of SWRs appear to "simulate" trajectories through the environment - called awake hippocampal replay - while the functional role of a majority of these SWRs remains unclear. Applying a novel probabilistic approach to characterize the spatio-temporal dynamics embedded in SWRs, we instead show that almost all SWRs of foraging rodents simulate such trajectories through the environment. Furthermore, these trajectories feature momentum, that is, inertia in their velocities, that mirrors the animals' natural movement. This stands in contrast to replay events during sleep which seem to follow Brownian motion without such momentum. Lastly, interpreting the replay trajectories in the context of navigational planning revealed that similar past analyses were biased by the heuristic SWR sub-selection. Overall, our approach provides a more complete characterization of the spatio-temporal dynamics within SWRs, highlights qualitative differences between sleep and awake replay, and ought to support future, more detailed, and less biased analysis of the role of awake replay in navigational planning.

DLTS: A Promising Technique for Understanding the Physics and Engineering of the Point Defects in Si and III-V Alloys

2007 ◽  
Vol 994 ◽  
Author(s):  
Aurangzeb Khan ◽  
Masafumi Yamaguchi
Keyword(s):  
Point Defects ◽  
Deep Level ◽  
Complete Characterization ◽  
Cell Parameters ◽  
Transient Spectroscopy ◽  
Almost All ◽  
Device Properties ◽  
Compound Materials

AbstractDeep level transient spectroscopy (DLTS) is the best technique for monitoring and characterizing deep levels introduced intentionally or occurring naturally in semiconductor materials and complete devices. DLTS has the advantage over all the techniques used to-date in that it fulfils almost all the requirements for a complete characterization of a deep centre and their correlation with the device properties. In particular the method can determine the activation energy of a deep level, its capture cross-section and concentration and can distinguish between traps and recombination centers.In this invited paper we provide an overview of the extensive R & D work that has been carrier out by the authors on the identification of the recombination and compensator centers in Si and III-V compound materials for space solar cells. In addition, we present an overview of key problems that remain in the understanding of the role of the point defects and their correlation with the solar cell parameters.

Real-time characterization of the spatio-temporal dynamics of deformable mirrors

2016 ◽  
Author(s):  
James Kilpatrick ◽  
Adela Apostol ◽  
Anatoliy Khizhnya ◽  
Vladimir Markov ◽  
Leonid Beresnev
Keyword(s):  
Real Time ◽  
Temporal Dynamics ◽  
Deformable Mirrors ◽  
Spatio Temporal

scholarly journals Percepción de los entrenadores de alto rendimiento de atletismo: caracterización de su perfil polifacético (Perception of high performance track and field coaches: characterization of their multifaceted profile)

Retos ◽  
2015 ◽  
pp. 42-47
Author(s):  
Angeles Filgueira Perez
Keyword(s):  
High Performance ◽  
Target Population ◽  
Track And Field ◽  
Personal Qualities ◽  
High Level ◽  
Almost All ◽  
Methodological Aspects ◽  
The Ideal

En el presente estudio se ha tratado de obtener una aproximación al perfil ideal del entrenador de alto rendimiento en atletismo. En el mundo del deporte de alta competición, el entrenador debe desarrollar funciones de maestro, técnico y líder, lo cual hace difícil delimitar sus competencias (conocimientos, habilidades y cualidades personales). Por tanto, la principal motivación de este trabajo es establecer el papel que debe desempeñar el entrenador para la preparación física, técnica, táctica, psicológica y moral del deportista de alto nivel. Para ello, se ha considerado como población objeto de estudio al conjunto de entrenadores de alto rendimiento que en el momento de la investigación estuviesen activo, ya que interesaba realizar este estudio desde su propia perspectiva. Los datos recogidos forman parte de una investigación más amplia, llevada a cabo mediante encuesta, para la que se diseñó un cuestionario de 78 preguntas en el que se abarcaban tres temas: el perfil del entrenador y del deportista, así como la figura del formador de entrenadores en el Practicum. En este trabajo nos centramos en el primer tema y el análisis de la información obtenida nos permite concluir que la que práctica totalidad de los entrenadores de atletismo consideran necesario dominar con precisión los aspectos técnico-metodológicos. Además, consideran que su ética profesional debe estar regida por los principios de autonomía y beneficencia, de modo que valores como la honestidad y la justicia deben primar en el desarrollo de sus funciones.Abstract: In the current study, we have tried to get an approximation of the ideal profile of high performance coaches in athletics. In the high-level sports world, the coach must develop the role of teacher, technician and leader,  which makes it difficult to delimit  his/her competencies (knowledge, skills and personal qualities). Therefore, the main motivation of this work is to define the role that the coach plays in relation  to the physical, technical, tactical, psychological and moral preparation of elite athletes. Keeping this aim as an objective, we have considered as the target population the high performance coaches who are active at the time of the investigation, since we were interested  in knowing their own perspective. The data that was collected is a part of a wider investigation, conducted by a survey, for which we designed a questionnaire of 78 questions divided on three topics: the profile of the coach and the athlete, as well as the figure of the coach educator in the Practicum. In this work, we focus on the first topic and the analysis of the information that we obtained allows us to conclude that almost all the track and field coaches find it necessary to dominate the technical and methodological aspects. They also consider that professional ethics must be governed by the principles of autonomy and care that values   like honesty and justice must prevail in the performance of their work.

Aortic disease: Aneurysm and dissection—role of MSCT

2021 ◽  
pp. 771-780
Author(s):  
Rocío Hinojar ◽  
Raimund Erbel
Keyword(s):  
Aortic Disease ◽  
Complete Characterization ◽  
Unexpected Finding ◽  
Aortic Diseases ◽  
Aortic Pathology ◽  
Life Threatening ◽  
Excellent Spatial Resolution ◽  
Widespread Availability

Multislice computed tomography (MSCT) is currently the preferred modality for diagnosis and complete characterization of aortic pathology because of its widespread availability, rapidity, excellent spatial resolution, and excellent accuracy for all aortic segments and different aortic diseases. Aortic disease often remains undiagnosed until a life-threatening complication occurs or the disease is an unexpected finding on imaging studies performed for other purposes. MSCT allows the measurement of the aortic wall and dimension and the evaluation of morphologic features and surrounding structures, even in very sick or unstable patients. It provides not only accurate and highly reproducible aortic measurements but also the evaluation of the wall and contents of an aneurysm, including thrombus, and surrounding structures.

scholarly journals Spatio-temporal modelling of the first Chikungunya epidemic in an intra-urban setting: The role of socioeconomic status, environment and temperature

2021 ◽  
Vol 15 (6) ◽  
pp. e0009537
Author(s):  
Laís Picinini Freitas ◽  
Alexandra M. Schmidt ◽  
William Cossich ◽  
Oswaldo Gonçalves Cruz ◽  
Marilia Sá Carvalho
Keyword(s):  
Temperature Effect ◽  
Temporal Dynamics ◽  
Urban Setting ◽  
Time Varying ◽  
Varying Coefficients ◽  
Temporal Models ◽  
Green Areas ◽  
Spatio Temporal ◽  
Time Varying Coefficients

Three key elements are the drivers of Aedes-borne disease: mosquito infestation, virus circulating, and susceptible human population. However, information on these aspects is not easily available in low- and middle-income countries. We analysed data on factors that influence one or more of those elements to study the first chikungunya epidemic in Rio de Janeiro city in 2016. Using spatio-temporal models, under the Bayesian framework, we estimated the association of those factors with chikungunya reported cases by neighbourhood and week. To estimate the minimum temperature effect in a non-linear fashion, we used a transfer function considering an instantaneous effect and propagation of a proportion of such effect to future times. The sociodevelopment index and the proportion of green areas (areas with agriculture, swamps and shoals, tree and shrub cover, and woody-grass cover) were included in the model with time-varying coefficients, allowing us to explore how their associations with the number of cases change throughout the epidemic. There were 13627 chikungunya cases in the study period. The sociodevelopment index presented the strongest association, inversely related to the risk of cases. Such association was more pronounced in the first weeks, indicating that socioeconomically vulnerable neighbourhoods were affected first and hardest by the epidemic. The proportion of green areas effect was null for most weeks. The temperature was directly associated with the risk of chikungunya for most neighbourhoods, with different decaying patterns. The temperature effect persisted longer where the epidemic was concentrated. In such locations, interventions should be designed to be continuous and to work in the long term. We observed that the role of the covariates changes over time. Therefore, time-varying coefficients should be widely incorporated when modelling Aedes-borne diseases. Our model contributed to the understanding of the spatio-temporal dynamics of an urban Aedes-borne disease introduction in a tropical metropolitan city.

scholarly journals The spatio-temporal dynamics of systemic thinking

2019 ◽  
Author(s):  
Gaëlle Vallée-Tourangeau ◽  
Frédéric Vallée-Tourangeau
Keyword(s):  
Information Processing ◽  
Temporal Dynamics ◽  
Information Processing Model ◽  
Systemic Thinking ◽  
Internal Representations ◽  
Final Version ◽  
Classical Information ◽  
Spatio Temporal

We argue that a radical departure from the classical information-processing model is untenable because higher-level cognition is fundamentally representation-based. However, we also argue that classical accounts of thinking put too great an emphasis on the role of internal representations and mental processing. Manuscript accepted for publication in Cybernetics & Human Knowing available at https://www.ingentaconnect.com/content/imp/chk/2014/00000021/F0020001/art00009. This article may not exactly replicate the final version published in the journal. It is not the copy of the record.

scholarly journals Functional and Structural Characterization of a Novel Isoamylase from Ostreococcus tauri and Role of the N-Terminal Domain

2020 ◽  
Vol 14 (1) ◽  
pp. 1-11
Author(s):  
Nicolas Hedín ◽  
Julieta Barchiesi ◽  
Diego F. Gomez-Casati ◽  
María V. Busi
Keyword(s):  
Crystallization Process ◽  
Biochemical Characterization ◽  
Carbohydrate Binding ◽  
Amino Acid Residues ◽  
Photosynthetic Organisms ◽  
Ostreococcus Tauri ◽  
The Family ◽  
Almost All

Background: The debranching starch enzymes, isoamylase 1 and 2 are well-conserved enzymes present in almost all the photosynthetic organisms. These enzymes are involved in the crystallization process of starch and are key components which remove misplaced α-1,6 ramifications on the final molecule. Aim: In this work, we performed a functional and structural study of a novel isoamylase from Ostreococcus tauri. Methods: We identified conserved amino acid residues possibly involved in catalysis. We also identified a region at the N-terminal end that resembles a Carbohydrate Binding Domain (CBM), which is more related to the family CBM48, but has no spatial conservation of the residues involved in carbohydrate binding. Results: The cloning, expression and biochemical characterization of this N-terminal region confirmed that it binds to polysaccharides, showing greater capacity for binding to amylopectin rather than total starch or amylose. Conclusion: This module could be a variant of the CBM48 family or it could be classified within a new CBM family.

Steady States of Sheared Active Nematics

2014 ◽  
Vol 6 (01) ◽  
pp. 75-86 ◽  
Author(s):  
Zhenlu Cui ◽  
Xiaoming Zeng ◽  
Jianbing Su
Keyword(s):  
Asymptotic Analysis ◽  
Numerical Simulations ◽  
Hydrodynamic Model ◽  
System Size ◽  
Complete Characterization ◽  
Steady States ◽  
Steady Shear

AbstractA continuum hydrodynamic model has been used to characterize flowing active nematics. The behavior of such a system subjected to a weak steady shear is analyzed. We explore the director structures and flow behaviors of the system in flow-aligning and flow tumbling regimes. Combining asymptotic analysis and numerical simulations, we extend previous studies to give a complete characterization of the steady states for both contractile and extensile particles in flow-aligning and flow-tumbling regimes. Another key prediction of this work is the role of the system size on the steady states of an active nematic system: if the system size is small, the velocity and the director angle files for both flow-tumbling contractile and extensile systems are similar to those of passive nematics; if the system is big, the velocity and the director angle files for flow-aligning contractile systems and tumbling extensile systems are akin to sheared passive cholesterics while they are oscillatory for flow-aligning extensile and tumbling contractile systems.

scholarly journals Complexity and polymorphisms for digraph constraint problems under some basic constructions

2016 ◽  
Vol 26 (07) ◽  
pp. 1395-1433 ◽  
Author(s):  
Marcel Jackson ◽  
Tomasz Kowalski ◽  
Todd Niven
Keyword(s):  
Directed Graphs ◽  
Complete Characterization ◽  
Constraint Satisfaction Problems ◽  
Local Consistency ◽  
First Order ◽  
Graph Theoretic ◽  
The Stability ◽  
Basic Graph

The role of polymorphisms in determining the complexity of constraint satisfaction problems is well established. In this context, we study the stability of CSP complexity and polymorphism properties under some basic graph theoretic constructions. As applications we observe a collapse in the applicability of algorithms for CSPs over directed graphs with both a total source and a total sink: the corresponding CSP is solvable by the “few subpowers algorithm” if and only if it is solvable by a local consistency check algorithm. Moreover, we find that the property of “strict width” and solvability by few subpowers are unstable under first-order reductions. The analysis also yields a complete characterization of the main polymorphism properties for digraphs whose symmetric closure is a complete graph.

Networks, Shocks, and Systemic Risk

2016 ◽  
pp. 568-608 ◽  
Author(s):  
Daron Acemoglu ◽  
Asuman Ozdaglar ◽  
Alireza Tahbaz-Salehi
Keyword(s):  
Systemic Risk ◽  
Complete Characterization ◽  
Unified Framework ◽  
Macroeconomic Risk ◽  
Prior Literature

This chapter develops a unified framework for the study of how network interactions can function as a mechanism for propagation and amplification of microeconomic shocks. The framework nests various classes of games over networks, models of macroeconomic risk originating from microeconomic shocks, and models of financial interactions. Under the assumption that shocks are small, the authors provide a fairly complete characterization of the structure of equilibrium, clarifying the role of network interactions in translating microeconomic shocks into macroeconomic outcomes. This characterization provides a ranking of different networks in terms of their aggregate performance. It also sheds light on several seemingly contradictory results in the prior literature on the role of network linkages in fostering systemic risk.

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