234 research outputs found
Information flow through a model of the C. elegans klinotaxis circuit
Understanding how information about external stimuli is transformed into
behavior is one of the central goals of neuroscience. Here we characterize the
information flow through a complete sensorimotor circuit: from stimulus, to
sensory neurons, to interneurons, to motor neurons, to muscles, to motion.
Specifically, we apply a recently developed framework for quantifying
information flow to a previously published ensemble of models of salt
klinotaxis in the nematode worm C. elegans. The models are grounded in the
neuroanatomy and currently known neurophysiology of the worm. The unknown model
parameters were optimized to reproduce the worm's behavior. Information flow
analysis reveals several key principles underlying how the models operate: (1)
Interneuron class AIY is responsible for integrating information about positive
and negative changes in concentration, and exhibits a strong left/right
information asymmetry. (2) Gap junctions play a crucial role in the transfer of
information responsible for the information symmetry observed in interneuron
class AIZ. (3) Neck motor neuron class SMB implements an information gating
mechanism that underlies the circuit's state-dependent response. (4) The neck
carries non-uniform distribution about changes in concentration. Thus, not all
directions of movement are equally informative. Each of these findings
corresponds to an experimental prediction that could be tested in the worm to
greatly refine our understanding of the neural circuit underlying klinotaxis.
Information flow analysis also allows us to explore how information flow
relates to underlying electrophysiology. Despite large variations in the neural
parameters of individual circuits, the overall information flow architecture
circuit is remarkably consistent across the ensemble, suggesting that
information flow analysis captures general principles of operation for the
klinotaxis circuit
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How much to copy from others?The role of partial copying in social learning
One of the major ways that people engage in adaptive problemsolving is by copying the solutions of others. Most of the workon this field has focused on three questions: when to copy, whoto copy from, and what to copy. However, how much to copyhas been relatively less explored. In the current research, weare interested in the consequences for a group when its mem-bers engage in social learning strategies with different tenden-cies to copy entire or partial solutions and different complex-ities of search problems. We also consider different networktopologies that affect the solutions visible to each member.Using a computational model of collective problem solving,we demonstrate that strategies where social learning involvespartial copying outperform strategies where individuals copyentire solutions. We analyze the exploration/exploitation dy-namics of these social learning strategies under the differentconditions
A Greedy Randomized Adaptive Search With Probabilistic Learning for solving the Uncapacitated Plant Cycle Location Problem
In this paper, we address the Uncapacitated Plant Cycle Location Problem. It is a location-routing problem aimed at determining a subset of locations to set up plants dedicated to serving customers. We propose a mathematical formulation to model the problem. The high computational burden required by the formulation when tackling large scenarios encourages us to develop a Greedy Randomized Adaptive Search Procedure with Probabilistic Learning Model. Its rationale is to divide the problem into two interconnected sub-problems. The computational results indicate the high performance of our proposal in terms of the quality of reported solutions and computational time. Specifically, we have overcome the best approach from the literature on a wide range of scenarios.</p
Decentralized Cooperative Metaheuristic for the Dynamic Berth Allocation Problem
The increasing demand of maritime transport and the great competition among port terminals force their managers to reduce costs by exploiting its resources accurately. In this environment, the Berth Allocation Problem, which aims to allocate and schedule incoming vessels along the quay, plays a relevant role in improving the overall terminal productivity. In order to address this problem, we propose Decentralized Cooperative Metaheuristic (DCM), which is a population-based approach that exploits the concepts of communication and grouping. In DCM, the individuals are organized into groups, where each individual shares information with its group partners. This grouping strategy allows to diversify as well as intensify the search in some regions by means of information shared among the individuals of each group. Moreover, the constrained relation for sharing information among individuals through the proposed grouping strategy allows to reduce computational resources in comparison to the `all to all' communication strategy. The computational experiments for this problem reveal that DCM reports high-quality solutions and identifies promising regions within the search space in short computational times
Psychometric properties of a revised Spanish 20-item Toronto Alexithymia Scale adaptation in multiple sclerosis patients
There have been a small number of investigations of alexithymia in multiple sclerosis
(MS) using the 20-item Toronto Alexithymia Scale (TAS-20). However, the TAS-20 factor structure
has not yet been evaluated in a MS patient sample, and earlier Spanish translations of this
instrument require some improvement. We aimed to evaluate the factorial validity and
reliability of an improved Spanish translation of the TAS-20 (the TAS-20-S). The TAS-20-S was
completed by 221 MS patients. Confirmatory factor analysis was used to compare the fit of six
different factor models. Internal consistency and retest reliability coefficients were also
computed. The correlated three-factor model and the higher-order factor model made up of
Difficulty Identifying Feelings, Difficulty Describing Feelings, and Externally Oriented Thinking
achieved the best fit. Alpha coefficients ranged between .87 and .67; mean inter-item
correlations ranged between .48 and .20; and retest correlations after 6 months ranged between
.61 and .52. A high degree of alexithymia was present in 18.1% of the sample. Reliability and the
traditional three-factor structure were demonstrated for the TAS-20-S, which can now be
recommended for assessing an aspect of emotional processing in MS patients.En la esclerosis múltiple (EM) son escasas las investigaciones centradas en evaluar la
alexitimia con la Escala de Alexitimia de Toronto (TAS-20). A pesar de ello, no se ha evaluado
aún su estructura factorial en dicha población y, además, las anteriores traducciones al español
necesitan modificaciones. Los objetivos del presente estudio fueron evaluar la validez factorial
y la fiabilidad de una traducción mejorada en español de la TAS-20 (la TAS-20-S), la cual fue
administrada en una muestra de 221 pacientes con EM. Se realizaron análisis factoriales confirmatorios para comparar el ajuste de seis modelos factoriales. También se calcularon coeficientes
de consistencia interna y de fiabilidad test-retest. Los modelos trifactorial correlacionado
y el de orden superior conformados por Dificultad en Identificar Sentimientos, Dificultad
en Describir Sentimientos y Pensamiento Externamente Orientado lograron el mejor ajuste. Los
coeficientes alfa oscilaron entre 0,87 y 0,67; las correlaciones medias inter-ítem entre 0,48 y
0,20; y las correlaciones test-retest tras 6 meses oscilaron entre 0,61 y 0,52. El 18,10% de la
muestra presentó niveles elevados de alexitimia. La TAS-20-S presentó una adecuada fiabilidad
así como la tradicional estructura trifactorial, por lo que su uso es ahora recomendable para
evaluar un aspecto del procesamiento emocional en EM.Ministerio de Educación, Cultura y Deporte de España Programa FPU (Formación del Profesorado Universitario
Novel population pharmacokinetic model for Linezolid in critically Ill patients and evaluation of the adequacy of the current dosing recommendation
Antimicrobial treatment in critically ill patients remains challenging. The aim of this study
was to develop a population pharmacokinetic model for linezolid in critically ill patients and to
evaluate the adequacy of current dosing recommendation (600 mg/12 h). Forty inpatients were
included, 23 of whom were subjected to continuous renal replacement therapies (CRRT). Blood and
effluent samples were drawn after linezolid administration at defined time points, and linezolid
levels were measured. A population pharmacokinetic model was developed, using NONMEM 7.3.
The percentage of patients that achieved the pharmacokinetic/pharmacodynamic (PK/PD) targets
was calculated (AUC24/MIC > 80 and 100% T>MIC). A two-compartment model best described the
pharmacokinetics of linezolid. Elimination was conditioned by the creatinine clearance and by the
extra-corporeal clearance if the patient was subjected to CRRT. For most patients, the standard dose
of linezolid did not cover infections caused by pathogens with MIC ≥ 2 mg/L. Continuous infusion
may be an alternative, especially when renal function is preserved
Mapping pediatric palliative care development in the WHO-European Region: children living in low-middle income countries are less likely to access it
Context: Approximately 170,000 children in need of palliative care die every year in Europe without access to it. This field remains an evolving specialty with unexplored development. Objectives: To conduct the first regional assessment of pediatric palliative care (PPC) development and provision using data from the European Association for Palliative Care atlas of palliative care 2019. Methods: Two surveys were conducted. The first one included a single question regarding PPC service provision and was addressed by European Association for Palliative Care atlas informants. The second one included 10 specific indicators derived from an open-ended interview and rating process; a specific network of informants was enabled and used as respondents. Data were analyzed and presented in the map of the figure. Results: Data on PPC service provision were gathered from 51 of 54 (94%) European countries. Additional data were collected in 34 of 54 (62%) countries. A total of 680 PPC services were identified including 133 hospices, 385 home care services, and 162 hospital services. Nineteen countries had specific standards and norms for the provision of PPC. Twenty-two countries had a national association, and 14 countries offered education for either pediatric doctors or nurses. In seven countries, specific neonatal palliative care referral services were identified. Conclusion: PPC provision is flourishing across the region; however, development is less accentuated in low-to-middle-income countries. Efforts need to be devoted to the conceptualization and definition of the models of care used to respond to the unmet need of PPC in Europe. The question whether specialized services are required or not should be further explored. Strategies to regulate and cover patients in need should be adapted to each national health system
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