scholarly journals Human value learning and representation reflects rational adaptation to task demands

2021 ◽  
Author(s):  
Keno Juechems ◽  
Tugba Altun ◽  
Rita Hira ◽  
Andreas Jarvstad
Keyword(s):  
Phase 1 ◽  
Task Demands ◽  
Computationally Efficient ◽  
Human Value ◽  
Wide Range ◽  
Local Contexts ◽  
Irrational Behaviour ◽  
Computational Resources ◽  
Value Learning ◽  
Value Representation

When making decisions about goods and actions, humans and animals often rely on internally represented values. However, to be useful across a wide range of contexts, these values need to be represented on an absolute scale – a coding scheme that is computationally costly. By contrast, representing values in a way that depends entirely on context is highly computationally efficient, but can lead to irrational behaviour when values need to be compared across contexts. Thus, an efficient learner would allocate limited computational resources only when needed according to their expectations about the future. Here, we test the hypothesis that value representation is not fixed, but rationally adapted to expectations in two human learning experiments. Unlike most lab-based tasks, participants could use their initial experience (Phase 1) to optimise behaviour (Phase 2). Phase 1 was designed to cause one group to expect only decisions within local contexts (relative code sufficient), and another group to expect choices across local contexts (relative code insufficient). Despite identical learning experiences, the group whose expectations included choices across local contexts, went on to learn absolute value representations, and learned more absolute-like representations than the other group. Human value representation is neither relative nor absolute, but efficiently and rationally tuned to task demands.

scholarly journals Towards Generative Design of Computationally Efficient Mathematical Models with Evolutionary Learning

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 28
Author(s):  
Anna V. Kalyuzhnaya ◽  
Nikolay O. Nikitin ◽  
Alexander Hvatov ◽  
Mikhail Maslyaev ◽  
Mikhail Yachmenkov ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Learning Approach ◽  
Model Structure ◽  
Evolutionary Learning ◽  
Learning Models ◽  
Computationally Efficient ◽  
Performance Models ◽  
Generative Design ◽  
Computational Resources ◽  
Machine Learning Models

In this paper, we describe the concept of generative design approach applied to the automated evolutionary learning of mathematical models in a computationally efficient way. To formalize the problems of models’ design and co-design, the generalized formulation of the modeling workflow is proposed. A parallelized evolutionary learning approach for the identification of model structure is described for the equation-based model and composite machine learning models. Moreover, the involvement of the performance models in the design process is analyzed. A set of experiments with various models and computational resources is conducted to verify different aspects of the proposed approach.

scholarly journals Foslevodopa/Foscarbidopa Is Well Tolerated and Maintains Stable Levodopa and Carbidopa Exposure Following Subcutaneous Infusion

2021 ◽  
pp. 1-8
Author(s):  
Matthew Rosebraugh ◽  
Wei Liu ◽  
Melina Neenan ◽  
Maurizio F. Facheris
Keyword(s):  
Steady State ◽  
Phase 1 ◽  
The United States ◽  
Therapeutic Window ◽  
Fixed Dose ◽  
Advanced Parkinson’S Disease ◽  
Subcutaneous Infusion ◽  
Study Results ◽  
Wide Range ◽  
Favorable Safety

Background: Foslevodopa/foscarbidopa, formerly known as ABBV-951, is a formulation of levodopa/carbidopa prodrugs with solubility that allows for subcutaneous (SC) infusion and is in development for the treatment of motor complications for patients with advanced Parkinson’s disease (aPD). Objective: The current work characterizes the levodopa (LD) and carbidopa (CD) pharmacokinetics (PK) following SC infusions of foslevodopa/foscarbidopa delivered at four different infusion rates in PD patients. Methods: This was a Phase 1, single ascending dose, single-blind study conducted in 28 adult male and female subjects at seven sites in the United States. Foslevodopa/foscarbidopa was administered via abdominal SC infusion in PD patients over 72 hours. Patients were stratified in 4 groups and received a fixed dose of foslevodopa/foscarbidopa based on their oral daily LD intake. Serial plasma PK samples were collected to assay for LD and CD concentrations. Safety and tolerability were assessed throughout the study. Results: LD exposure quickly reached steady state and remained stable with minimal fluctuations. Foslevodopa/foscarbidopa infusion provides stable LD and CD exposures compared to oral LD/CD dosing with the average steady-state exposure ranging from 747-4660 ng/mL for the different groups. Conclusion: Foslevodopa/foscarbidopa was able to provide stable LD and CD exposures in PD patients over 72 hours via SC route of delivery with very low fluctuation in LD concentration level across a wide range of clinically relevant exposures. Foslevodopa/foscarbidopa had a favorable safety profile. The low PK fluctuation following foslevodopa/foscarbidopa infusion is expected to maintain LD exposure to treat aPD patients within a narrow therapeutic window.

scholarly journals Privacy-Aware Multidimensional Mobile Service Quality Prediction and Recommendation in Distributed Fog Environment

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Wenwen Gong ◽  
Lianyong Qi ◽  
Yanwei Xu
Keyword(s):  
Service Selection ◽  
Locality Sensitive Hashing ◽  
Mobile Service ◽  
Service Recommendation ◽  
User Privacy ◽  
Service Usage ◽  
Selection Decisions ◽  
Wide Range ◽  
Cross Platform ◽  
Computational Resources

With the ever-increasing popularity of mobile computing technology, a wide range of computational resources or services (e.g., movies, food, and places of interest) are migrating to the mobile infrastructure or devices (e.g., mobile phones, PDA, and smart watches), imposing heavy burdens on the service selection decisions of users. In this situation, service recommendation has become one of the promising ways to alleviate such burdens. In general, the service usage data used to make service recommendation are produced by various mobile devices and collected by distributed edge platforms, which leads to potential leakage of user privacy during the subsequent cross-platform data collaboration and service recommendation process. Locality-Sensitive Hashing (LSH) technique has recently been introduced to realize the privacy-preserving distributed service recommendation. However, existing LSH-based recommendation approaches often consider only one quality dimension of services, without considering the multidimensional recommendation scenarios that are more complex but more common. In view of this drawback, we improve the traditional LSH and put forward a novel LSH-based service recommendation approach named SerRecmulti-qos, to protect users’ privacy over multiple quality dimensions during the distributed mobile service recommendation process.

Efficient computation of Faith's phylogenetic diversity with applications in characterizing microbiomes

2021 ◽  
pp. gr.275777.121
Author(s):  
George W Armstrong ◽  
Kalen Cantrell ◽  
Shi Huang ◽  
Daniel McDonald ◽  
Niina Haiminen ◽  
...  
Keyword(s):  
Carbon Footprint ◽  
Phylogenetic Diversity ◽  
Alpha Diversity ◽  
Previous Method ◽  
Metagenomic Data ◽  
Efficient Computation ◽  
Computationally Efficient ◽  
Dataset Size ◽  
Computational Resources ◽  
Older Populations

The number of publicly available microbiome samples is continually growing. As dataset size increases, bottlenecks arise in standard analytical pipelines. Faith’s phylogenetic diversity is a highly utilized phylogenetic alpha diversity metric that has thus far failed to effectively scale to trees with millions of vertices. Stacked Faith's Phylogenetic Diversity (SFPhD) enables calculation of this widely adopted diversity metric at a much larger scale by implementing a computationally efficient algorithm. The algorithm reduces the amount of computational resources required, resulting in more accessible software with a reduced carbon footprint, as compared to previous approaches. The new algorithm produces identical results to the previous method. We further demonstrate that the phylogenetic aspect of Faith's PD provides increased power in detecting diversity differences between younger and older populations in the FINRISK study's metagenomic data.

Vibration Suppression of an Elastically Supported Beam With Closely Spaced Natural Frequencies

2020 ◽  
Author(s):  
Haizhou Liu ◽  
Hao Gao
Keyword(s):  
Natural Frequencies ◽  
Vibration Suppression ◽  
Fixed Point Theory ◽  
Dynamic Performance ◽  
Point Theory ◽  
Primary System ◽  
Computationally Efficient ◽  
Wide Range ◽  
Univariate Optimization ◽  
Elastically Supported

Abstract Vibration suppression of distributed parameter systems is of great interest and has a wide range of applications. The dynamic performance of a primary system can be improved by adding dynamic vibration absorbers (DVA). Although the relevant topics have been studied for decades, the trade-off between capability of suppressing multiple resonant peaks and complexity of absorbers has not been well addressed. In this paper, the vibration suppression problem of a uniform Euler-Bernoulli beam with closely spaced natural frequencies is investigated. To achieve desired vibration reduction, a two-DOF DVA is connected to the beam through a pair of a spring and a dashpot. By introducing a virtual ground spring, the parameters of the absorber are determined via extended fixed point theory. The proposed method only requires univariate optimization and is computationally efficient. Numerical examples conducted verify the viability of the proposed method and the effectiveness of a two-DOF DVA in suppressing double resonances.

scholarly journals Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 587 ◽  
Author(s):  
Malgorzata Straka ◽  
Benjamin Shafer ◽  
Srikanth Vasudevan ◽  
Cristin Welle ◽  
Loren Rieth
Keyword(s):  
Electrochemical Impedance ◽  
Iridium Oxide ◽  
Support Vector ◽  
Impedance Spectra ◽  
Computationally Efficient ◽  
Wide Range ◽  
Tissue Interface ◽  
Computationally Efficient Algorithms ◽  
Physical Changes

Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to false positives. We implanted cohorts of five iridium oxide (IrOx) and six platinum (Pt) Utah arrays into the sciatic nerve of rats, and collected the electrochemical impedance spectroscopy (EIS) up to 12 weeks or until array failure. We developed a method to classify the shapes of the magnitude and phase spectra, and correlated the classifications to circuit models and electrochemical processes at the interface likely responsible. We found categories of EIS characteristic of iridium oxide tip metallization, platinum tip metallization, tip metal degradation, encapsulation degradation, and wire breakage in the lead. We also fitted the impedance spectra as features to a fine-Gaussian support vector machine (SVM) algorithm for both IrOx and Pt tipped arrays, with a prediction accuracy for categories of 95% and 99%, respectively. Together, this suggests that these simple and computationally efficient algorithms are sufficient to explain the majority of variance across a wide range of EIS data describing Utah arrays. These categories were assessed over time, providing insights into the degradation and failure mechanisms for both the electrode–tissue interface and wire bundle. Methods developed in this study will allow for a better understanding of how EIS can characterize the physical changes to electrodes in vivo.

scholarly journals Multilayer modelling of waves generated by explosive submarine volcanism

2021 ◽  
Author(s):  
Matthew W. Hayward ◽  
Colin N. Whittaker ◽  
Emily M. Lane ◽  
William Power ◽  
Stéphane Popinet ◽  
...  
Keyword(s):  
Underwater Explosion ◽  
Theoretical Models ◽  
Mono Lake ◽  
Tsunami Source ◽  
Computationally Efficient ◽  
Relative Significance ◽  
Submarine Volcanism ◽  
Wave Characteristics ◽  
Wide Range ◽  
Source Models

Abstract. Theoretical source models of underwater explosions are often applied in studying tsunami hazards associated with submarine volcanism; however, their use in numerical codes based on the shallow water equations can neglect the significant dispersion of the generated wavefield. A non-hydrostatic multilayer method is validated against a laboratory-scale experiment of wave generation from instantaneous disturbances and at field-scale submarine explosions at Mono Lake, California, utilising the relevant theoretical models. The numerical method accurately reproduces the range of observed wave characteristics for positive disturbances and suggests a previously unreported relationship of extended initial troughs for negative disturbances at low dispersivity and high nonlinearity parameters. Satisfactory amplitudes and phase velocities within the initial wave group are found using underwater explosion models at Mono Lake. The scheme is then applied to modelling tsunamis generated by volcanic explosions at Lake Taupō, New Zealand, for a magnitude range representing ejecta volumes between 0.04–0.4 km3. Waves reach all shores within 15 minutes with maximum incident crest amplitudes around 4 m at shores near the source. This work shows that the multilayer scheme used is computationally efficient and able to capture a wide range of wave characteristics, including dispersive effects, which is necessary when investigating submarine explosions. This research therefore provides the foundation for future studies involving a rigorous probabilistic hazard assessment to quantify the risks and relative significance of this tsunami source mechanism.

scholarly journals Assessing the Sensitivity of Stall-Regulated Wind Turbine Power to Blade Design Using High-Fidelity Computational Fluid Dynamics

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Andrea G. Sanvito ◽  
Giacomo Persico ◽  
M. Sergio Campobasso
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Field Testing ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
High Fidelity ◽  
Blade Design ◽  
Computationally Efficient ◽  
Wind Speeds ◽  
Wide Range

Abstract This study provides a novel contribution toward the establishment of a new high-fidelity simulation-based design methodology for stall-regulated horizontal axis wind turbines. The aerodynamic design of these machines is complex, due to the difficulty of reliably predicting stall onset and poststall characteristics. Low-fidelity design methods, widely used in industry, are computationally efficient, but are often affected by significant uncertainty. Conversely, Navier–Stokes computational fluid dynamics (CFD) can reduce such uncertainty, resulting in lower development costs by reducing the need of field testing of designs not fit for purpose. Here, the compressible CFD research code COSA is used to assess the performance of two alternative designs of a 13-m stall-regulated rotor over a wide range of operating conditions. Validation of the numerical methodology is based on thorough comparisons of novel simulations and measured data of the National Renewable Energy Laboratory (NREL) phase VI turbine rotor, and one of the two industrial rotor designs. An excellent agreement is found in all cases. All simulations of the two industrial rotors are time-dependent, to capture the unsteadiness associated with stall which occurs at most wind speeds. The two designs are cross-compared, with emphasis on the different stall patterns resulting from particular design choices. The key novelty of this work is the CFD-based assessment of the correlation among turbine power, blade aerodynamics, and blade design variables (airfoil geometry, blade planform, and twist) over most operational wind speeds.

scholarly journals Efficient approximations for stationary single-channel Ca2+ nanodomains across length scales

2020 ◽  
Author(s):  
Y Chen ◽  
C Muratov ◽  
V Matveev
Keyword(s):  
Parameter Space ◽  
Single Channel ◽  
Asymptotic Series ◽  
Rational Functions ◽  
Great Accuracy ◽  
Model Parameters ◽  
Relevant Parameter ◽  
Buffer Concentration ◽  
Computationally Efficient ◽  
Wide Range

ABSTRACTWe consider the stationary solution for the Ca2+ concentration near a point Ca2+ source describing a single-channel Ca2+ nanodomain, in the presence of a single mobile Ca2+ buffer with one-to-one Ca2+ binding. We present computationally efficient approximants that estimate stationary single-channel Ca2+ nanodomains with great accuracy in broad regions of parameter space. The presented approximants have a functional form that combines rational and exponential functions, which is similar to that of the well-known Excess Buffer Approximation and the linear approximation, but with parameters estimated using two novel (to our knowledge) methods. One of the methods involves interpolation between the short-range Taylor series of the buffer concentration and its long-range asymptotic series in inverse powers of distance from the channel. Although this method has already been used to find Padé (rational-function) approximants to single-channel Ca2+ and buffer concentration, extending this method to interpolants combining exponential and rational functions improves accuracy in a significant fraction of the relevant parameter space. A second method is based on the variational approach, and involves a global minimization of an appropriate functional with respect to parameters of the chosen approximations. Extensive parameter sensitivity analysis is presented, comparing these two methods with previously developed approximants. Apart from increased accuracy, the strength of these approximants is that they can be extended to more realistic buffers with multiple binding sites characterized by cooperative Ca2+ binding, such as calmodulin and calretinin.STATEMENT OF SIGNIFICANCEMathematical and computational modeling plays an important role in the study of local Ca2+ signals underlying vesicle exocysosis, muscle contraction and other fundamental physiological processes. Closed-form approximations describing steady-state distribution of Ca2+ in the vicinity of an open Ca2+ channel have proved particularly useful for the qualitative modeling of local Ca2+ signals. We present simple and efficient approximants for the Ca2+ concentration in the presence of a mobile Ca2+ buffer, which achieve great accuracy over a wide range of model parameters. Such approximations provide an efficient method for estimating Ca2+ and buffer concentrations without resorting to numerical simulations, and allow to study the qualitative dependence of nanodomain Ca2+ distribution on the buffer’s Ca2+ binding properties and its diffusivity.

scholarly journals Using Eye-Tracking Measures to Predict Reading Comprehension

2021 ◽  
Author(s):  
Diane Caroline Meziere ◽  
Lili Yu ◽  
Erik Reichle ◽  
Titus von der Malsburg ◽  
Genevieve McArthur
Keyword(s):  
Reading Comprehension ◽  
Eye Tracking ◽  
Cognitive Skills ◽  
Common Good ◽  
Sentence Comprehension ◽  
Reading Speed ◽  
Task Demands ◽  
Wide Range ◽  
Comprehension Tests ◽  
Reading Comprehension Tests

Research on reading comprehension assessments suggests that they measure overlapping but not identical cognitive skills. In this paper, we examined the potential of eye-tracking as a tool for assessing reading comprehension. We administered three widely-used reading comprehension tests with varying task demands to 79 typical adult readers while monitoring their eye movements. In the York Assessment for Reading Comprehension (YARC), participants were given passages of text to read silently, followed by comprehension questions. In the Gray Oral Reading Test (GORT-5), participants were given passages of text to read aloud, followed by comprehension questions. In the sentence comprehension subtest of the Wide Range Achievement Test (WRAT-4), participants were given sentences with a missing word to read silently, and had to provide the missing word (i.e., a cloze task). Results from linear models predicting comprehension scores from eye-tracking measures yielded different patterns of results between the three tests. Models with eye-tracking measures always explained significantly more variance compared to baseline models with only reading speed, with R-squared 4 times higher for the YARC, 3 times for the GORT, and 1.3 times for the WRAT. Importantly, despite some similarities between the tests, no common good predictor of comprehension could be identified across the tests. Overall, the results suggest that reading comprehension tests do not measure the same cognitive skills to the same extent, and that participants adapted their reading strategies to the tests’ varying task demands. Finally, this study suggests that eye-tracking may provide a useful alternative for measuring reading comprehension.

Sign in / Sign up

Export Citation Format

Share Document