Response Fluctuations Research Articles

Perceived Usefulness of Multimodal Voice Assistant Technology

Smart speaker devices are appealing to consumers, but the perceived usefulness of the multimodal voice experience is not fully understood. The purpose of this study was to evaluate the extent to which cognitive load, the relevance of visual information, and personality influence the perceived usefulness of multimodal voice assistant technology in a within-subjects repeated measures design. A multimodal voice prototype was created to answer the question, “What are some extreme weather conditions?” Nine variants, including 3, 5 and 7 system responses with relevant, irrelevant or no information presented on a screen were included. Three tasks were embedded within each condition (Stroop task, sort M&Ms and no task). Perceived usefulness score, recall, personality score, and fluctuations in galvanic skin response (GSR) values were the subjective and objective measures. The findings suggest that when there’s a smaller number of responses/words for the participant to attend to, and subsequently recall, in addition to relevant visual feedback to aid in that recall, they perceive the voice assistant experience to be more useful, while task conducted exhibits marginal significance in determining PU. Scores of conscientiousness, openness to experience, agreeableness, and neuroticism were successful in predicting some variation in the PU responses, while GSR data was not. It is highly recommended that UX designers of the multimodal interface create succinct voice responses with relevant visual feedback to accompany it, and to keep the main use cases of these products in mind to increase the experience’s PU and subsequent behavioral intention to use the product.

Development and Validation of a New LC-MS/MS Analytical Method for Direct-Acting Antivirals and Its Application in End-Stage Renal Disease Patients.

The effectiveness of direct-acting antivirals (DAAs) is not well established in end-stage renal disease (ESRD) patients. Assessment of the plasma concentrations may support understanding of their therapeutic outcomes in this population. The aim of this study is to develop a direct, yet matrix-effect tolerant, analytical method for determining DAAs in the plasma of ESRD patients while maintaining a moderate cost per sample and with an improved analyte extraction recovery. In this study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the analysis of ombitasvir (OMB), paritaprevir (PRT) and ritonavir (RIT) in plasma. Sample preparation was performed using the liquid-liquid extraction (LLE) method. Isocratic separation was performed using a mixture of methanol and 10mM ammonium acetate (79:21, v/v) followed by MS/MS detection. The method was validated and applied to determine DAAs in the plasma of ESRD patients (n = 7). The developed method was linear (r2 > 0.995), accurate (89.4 ± 7.8 to 108.3 ± 3.0) and precise (% CV 0.9-15.0) and showed improved recovery (> 80) over previously published ones in the range 5-250, 30-1,500, 20-1,000ng/mL for OMB, PRT and RIT, respectively. Relative matrix effect was absent, and the method accurately determined the three DAAs in real-life samples (n = 7). An efficient analytical method for the determination of DAAs is presented. The method overcomes the potential analytical response fluctuation in ESRD. The developed method show improved extraction recoveries and is suitable for routine application in developing economies where hepatitis C virus is most prevalent.

Maintenance of broadband detection in photonic time-stretched coherent radar employing phase diversity.

Frequency response fluctuation in a radar system distorts the envelope of the output signal after matched filtering, thereby impairing its broadband detection performance. Simulations are made under various types and degrees of fluctuation. The results prove that the peak power and range resolution of broadband detection suffer different levels of deterioration. Moreover, simulation results also show that two outputs with orthogonal phase diversity have complementary variation trends and their combination can effectively enhance the broadband detection performance. Based on theoretical analysis, we employ the combination of two orthogonal phase diversity to achieve broadband detection in the photonic time-stretched coherent radar. Compared with using an ordinary modulator, a dual-output-Mach-Zehnder-modulator-based system makes the dispersion-penalty-induced frequency response fluctuation decrease by 9.7 dB. For single target detection, the peak power is increased by 6.7 dB and the range resolution is improved from 8.4 cm to 4.8 cm. For two-target detection, a 6-cm spatial interval is distinguished reliably.

Full-scale steel column tests under simulated horizontal and vertical earthquake loadings

This paper presents an experimental study to evaluate the vertical ground motion effects on steel wide-flange section columns in lower stories of steel frames. Eight full-scale specimens were tested utilizing the Multiple Usage Structural Testing (MUST) equipment, which can properly apply loading in both horizontal and vertical directions. Three cyclic lateral loading tests under constant axial load of 15% to 25% of nominal axial yield capacity were conducted to investigate the basic hysteretic behaviors. Five specimens were tested by pseudo-dynamic hybrid simulation with both horizontal and vertical excitations and an initial gravity load of 15% or 25% axial capacity. The failure mode of specimens tested by cyclic loading was notably influenced by the section compactness. Columns with thinner elements failed due to significant local buckling near the column ends corresponding to a drift ratio of 6% or even larger, while columns with thicker elements suffered rupture in the welding heat affected zones near column ends corresponding to a drift ratio of 4%. During the pseudo-dynamic hybrid loading with ground motions using the records of Imperial Valley earthquake and Northridge earthquake records, no rupture was observed. Lateral hysteretic response fluctuation was clearly observed in the pseudo-dynamic hybrid tests due to the inputs of both horizontal and the vertical ground motions. The pulse-type seismic input caused large residual displacements of the full-scale column specimens. Vertical ground motion also led to significant variations in axial loads, indicating the importance to study the seismic behavior of steel columns under realistic ground motion inputs.

Flexible chemiresistive sensor of polyaniline coated filter paper prepared by spraying for fast and non-contact detection of nitroaromatic explosives

Both bending stability and high sensitivity are two important problems to be solved in developing flexible sensors. The flexible sensor based on flower-like polyaniline coated filter paper (PCFP) was developed by spraying for the first time, achieving the non-contact and fast detection of nitroaromatic explosives. Hierarchical structure, high permeability of filter paper and the interaction between amino groups of PANI and nitro groups of nitroaromatic explosives contributed to the sensitive and fast response to 2, 4, 6-trinitrotoluene (TNT), picric acid (PA) and 2, 4-dinitrotoluene (DNT) at room temperature. The responses of PCFP to TNT, PA and DNT run up to about 237.7, 100.6 and 80.1%, respectively. The average response time and recovery time to TNT, PA and DNT are no more than 8.1 and 1.9 s, respectively. The theoretical limit of detection for TNT and PA is 0.094 and 0.029 ppb, respectively. More importantly, the special interlaced flower-like structures of polyaniline contributed to the good flexural stability. The response fluctuation to TNT, PA and DNT do not exceed 7% in the bending process and the decreases of responses are less than 7.9% after 2000 bends of 40°. In addition, the spraying method is suitable for economical, efficient and large-scale preparation of paper-based flexible sensors.

A method to depress the transmitting voltage response fluctuation of a double excitation piezoelectric transducer

To depress the fluctuation of the transmitting voltage response (TVR) for a double excitation broadband transducer, an electrical method is proposed in this paper by connecting resistances in series with the upper and lower piezoelectric ceramic stacks of the transducer. The equivalent circuit and the finite element method are used to analyze the effect of the resistances on TVR, and the optimizing values of the resistances connected in series with the piezoelectric ceramic stacks are obtained. The results obtained by equivalent circuit model and finite element simulation show that the fluctuation of the TVR for the double excitation transducer is obviously depressed when resistances are connected in series with the piezoelectric ceramic stacks. Based on the computational results, a double excitation broadband transducer with a working frequency range from 14 kHz to 36 kHz is made, and the TVR of the transducer is measured to validate the proposed method. The experimental results imply that the fluctuation of the TVR within the working frequency band for a double excitation piezoelectric transducer decreased from 12 dB to 7.3 dB.

Impact of channel fluctuations on channel estimation errors in underwater acoustic communications

Channel estimation is critical to achieve high data rate acoustic communications in the ocean. Channel estimates are often utilized to address the distortions induced by multipath propagation in various communication receivers. Therefore, accurate channel estimation is often the prerequisite for reliable coherent acoustic communications. Many efforts have been devoted to either characterizing the acoustic channel or developing high-performance channel estimation algorithms. However, limited work has been directed to investigate effect of channel fluctuations on estimation performance. Here we seek to quantify the impact of channel fluctuations on least squares channel estimators. A new metric, channel variation ratio, is used to describe the rate of fluctuations in the acoustic impulse responses. We investigate the relationship between the mean squared error (MSE) of the channel estimates and the channel variation ratio. We show the new metric can be used to predict channel estimation MSE for least squares channel estimators. Numeric results also show that there exists an optimal channel length with the minimum estimation error for fluctuating acoustic channels. Both computer simulations and experimental data have been used to validate the findings. [Work supported by the National Science Foundation CNS# 1704076.]

Detection of a High-Turnover Serotonin Circuit in the Mouse Brain Using Mass Spectrometry Imaging.

SummaryMonoamine neurotransmitters are released by specialized neurons regulating behavioral, motor, and cognitive functions. Although the localization of monoaminergic neurons in the brain is well known, the distribution and kinetics of monoamines remain unclear. Here, we generated a murine brain atlas of serotonin (5-HT), dopamine (DA), and norepinephrine (NE) levels using mass spectrometry imaging (MSI). We found several nuclei rich in both 5-HT and a catecholamine (DA or NE) and identified the paraventricular nucleus of the thalamus (PVT), where 5-HT and NE are co-localized. The analysis of 5-HT fluctuations in response to acute tryptophan depletion and infusion of isotope-labeled tryptophan in vivo revealed a close kinetic association between the raphe nuclei, PVT, and amygdala but not the other nuclei. Our findings imply the existence of a highly dynamic 5-HT-mediated raphe to PVT pathway that likely plays a role in the brain monoamine system.

Dynamic analysis of a hydraulic motor drive with variable inertia flywheel

A flywheel is presented in this article, which can adaptively generate variable inertia in response to the application requirements in a hydraulic drive. The said flywheel consists of four sliders in the guide track of a host flywheel frame which change its position as the rotational speed of the flywheel varies. The varying distance between the slider and the center of rotation leads to a variable inertial mass. This passive inertial mass has a potential to reduce the speed fluctuations of the drive. A comparative study has been made on the effects of the variable inertia flywheel on the hydraulic motor speed fluctuations with that of the fixed inertia flywheel. In this respect, a bond graph model of the hydraulic motor drive with the variable inertia flywheel and the fixed inertia flywheel is developed to analyze their performances. The variable inertia generated by the variable inertia flywheel reduces the hydraulic motor speed fluctuations in response to the changes in the excitation inputs. The tests were conducted to validate the model for step change in speed of the hydraulic motor. The test results of the hydraulic motor speed response are found in good agreement with the predicted response. The proposed design of the flywheel reduces the peak speed of the hydraulic motor that enhances the reliability and performance of the drive.

The Concurrent Control of Motion and Contact Force in the Presence of Predictable Disturbances.

The simultaneous control of force and motion is important in everyday activities when humans interact with objects. While many studies have analyzed the control of movement within a perturbing force field, few have investigated its dual aspects of controlling a contact force in nonisometric conditions. The mechanism by which the central nervous system controls forces during movements is still unclear, and it can be elucidated by estimating the mechanical properties of the arm during tasks with concurrent motion and contact force goals. We investigate how arm mechanics change when a force control task is accomplished during low-frequency positional perturbations of the arm. Contrary to many force regulation algorithms implemented in robotics, where contact impedance is decreased to reduce force fluctuations in response to position disturbances, we observed a steady increase of arm endpoint stiffness as the task progressed. Based on this evidence, we propose a theoretical framework suggesting that an internal model of the perturbing trajectory is formed. We observed that force regulation in the presence of predictable positional disturbances is implemented using a position control strategy together with the modulation of the endpoint stiffness magnitude, where the direction of the endpoint stiffness ellipse's major axis is oriented toward the desired force.

Electrochemically reconfigurable architected materials.

Architected materials can actively respond to external stimuli-such as mechanical forces, hydration and magnetic fields-by changing their geometries and thereby achieve novel functionalities. Such transformations are usually binary and volatile because they toggle between 'on' and 'off' states and require persistent external stimuli. Here we develop three-dimensional silicon-coated tetragonal microlattices that transform into sinusoidal patterns via cooperative beam buckling in response to an electrochemically driven silicon-lithium alloying reaction. In situ microscopy reveals a controllable, non-volatile and reversible structural transformation that forms multiple ordered buckling domains separated by distorted domain boundaries. We investigate the mechanical dynamics of individual buckling beams, cooperative coupling among neighbouring beams, and lithiation-rate-dependent distributions of domain sizes through chemo-mechanical modelling and statistical mechanics analysis. Our results highlight the critical role of defects and energy fluctuations in the dynamic response of architected materials. We further demonstrate that domain boundaries can be programmed to form particular patterns by pre-designing artificial defects, and that a variety of reconfigurational degrees of freedom can be achieved through micro-architecture design. This framework enables the design, fabrication, modelling, behaviour prediction and programming of electrochemically reconfigurable architected materials, and could open the way to beyond-intercalation battery electrodes, tunable phononic crystals and bio-implantable devices.

Very complex internal standard response variation in LC-MS/MS bioanalysis: root cause analysis and impact assessment.

Internal standards (ISs) are essential for the development and use of reliable quantitative bioanalytical LC-MS/MS methods, because they correct for fluctuations in the analytical response that are caused by variations in experimental conditions. Sample-to-sample differences in the IS response are thus to be expected, but a large variability often is an indication of nonoptimal sample handling or analysis settings. This paper discusses a number of cases of very complex variation of IS responses that could be attributed to analytical problems such as injection errors and sample inhomogeneity, and matrix-related issues such as degradation and increased ionization efficiency. A decision tree is proposed to help find the underlying root cause for extreme IS variability.

An Adaptive Proper Orthogonal Decomposition Method for Evaluating Variability Bounds of Antenna Responses

Parameter uncertainties introduced by the manufacturing process will lead to the fluctuation of an actual antenna response. Efficient methods are, thus, required during the design phase to evaluate the variability bounds. This letter proposes an adaptive proper orthogonal decomposition (APOD) method to estimate the variability bounds of the radiation patterns and reflection coefficients of the antenna with uncertain parameters. In this method, a parameterized reduced order model (PROM), as a function of the uncertain parameters, is automatically constructed using a Voronoi diagrams-based multipoint sampling algorithm. Then, the PROM-based Monte Carlo analysis is applied to obtain the variability bounds of the antenna responses. Numerical simulations and experimental tests are conducted, and the results show that the proposed APOD method can obtain comparable accuracy, but achieve a fast speed enhancement, compared with the existing methods.

Recovering from Scandals: Twitter Coverage of Oxfam and Save the Children Scandals

We examine Twitter data to assess the impact of media exposes on the reputations of two international nonprofits, Oxfam and Save the Children (STC). Using a random sample of 6794 Tweets, we study the daily gap between positive and negative sentiments expressed towards these organizations. The “unweighted gap” and the “weighted gap” (weighted by the number of followers) of the Twitter handle follow broadly the same trajectory with high fluctuation in response to new negative or positive media stories. Twitter handles with large audiences amplify variability in weighted gap. While Oxfam’s reputation did not fully recover to pre-Haiti levels even 6 months after the scandal, STC’s reputation returned to pre-scandal levels in 8 days, although it fluctuated in response to new revelations. Overall, reputation recovery for both organizations was aided when they received celebrity endorsements and focused public attention on their positive activities, especially by linking to visible global events.

Finite field formalism for bulk electrolyte solutions

The manner in which electrolyte solutions respond to electric fields is crucial to understanding the behavior of these systems both at, and away from, equilibrium. The present formulation of linear response theory for such systems is inconsistent with common molecular dynamics (MD) implementations. Using the finite field formalism, suitably adapted for finite temperature MD, we investigate the response of bulk aqueous NaCl solutions to both finite Maxwell (E) and electric displacement (D) fields. The constant E Hamiltonian allows us to derive the linear response relation for the ionic conductivity in a simple manner that is consistent with the forces used in conventional MD simulations. Simulations of a simple point charge model of an electrolyte solution at constant E yield conductivities at infinite dilution within 15% of experimental values. The finite field approach also allows us to measure the solvent’s dielectric constant from its polarization response, which is seen to decrease with increasing ionic strength. Comparison of the dielectric constant measured from polarization response vs polarization fluctuations enables direct evaluation of the dynamic contribution to this dielectric decrement, which we find to be small but not insignificant. Using the constant D formulation, we also rederive the Stillinger-Lovett conditions, which place strict constraints on the coupling between solvent and ionic polarization fluctuations.

Macroeconomic implications of dynamically inconsistent preferences

Despite the widespread use of models of intertemporal choices in economics, previous studies have assumed that intertemporal preferences are dynamically consistent. This paper provides a fresh perspective on propagation mechanisms of a typical macroeconomic shock in a model with dynamically inconsistent preferences. To this end, I develop a prototypical neoclassical model that features dynamically inconsistent preferences to explore dynamic responses of key macro-aggregates, discounted cumulative effects and some characteristics of aggregate fluctuations in response to a technology shock. The main findings reveal that (a) consumption and investment in the proposed model show a larger increase than those in a standard neoclassical model; (b) unlike the standard model, the proposed model yields a short-run decline in labor, which is corroborated by previous studies; (c) all of these dynamic responses in the proposed model deliver smaller cumulative output effects; (d) the proposed model does a reasonably good job of matching key characteristics of aggregate fluctuations with the counterparts observed in the postwar U.S. data. The present-bias and sophistication effects are the linchpin of these main results. Various analyses on a set of different parameter values are also discussed.

Management of Parkinson's disease a review of current and new therapies.

The management of Parkinson's disease has undergone recent changes with the advent of new therapies, both pharmacotherapy and surgery. Available interventions are discussed. Levodopa remains the mainstay of therapy. New drugs include the dopamine agonists and COMT inhibitors. New dopamine agonists which may have a levodopa "sparing effect;" it has been suggested that some of the drugs should be considered as first line treatments for newly diagnosed Parkinson's disease patients. We review roles of these drugs. The concept of neuroprotection in neurodegenerative disorders such as Parkinson's disease became popular in the mid 1980s and it is hoped that eventually therapy will be directed at slowing progression of the disease. A great deal more work needs to be done before a suitable agent is identified as being neuroprotective. Potential neuroprotective agents are reviewed. Surgical therapies for Parkinson's disease consisting of various forms of lesion surgery as well as stimulation procedures are reviewed. Complications of drug therapy include motor problems such as motor response fluctuations, as well as psychiatric complications including levodopa-induced psychosis. Atypical neuroleptic agents and ECT for psychiatric syndromes associated with Parkinson's disease are discussed. Algorithms for the management of early disease as well as the management of psychosis in Parkinson's disease are included. Treatment options for advanced disease are tabulated.

Complex dynamical interplay between solid particles and flow in driven granular suspensions

Granular materials immersed in a fluid are ubiquitous in daily life, industry, and nature. They include food processing, pastes, cosmetics, paints, concretes, cements, muds, wet sands, snows, landslides, and lava flow. They are known to exhibit a rich variety of complex rheological behavior, but the role of a fluid component in such behavior has remained poorly understood due to the nonlocal and many-body nature of hydrodynamic interactions between solid particles mediated by the fluid. We address this fundamental problem by comparing the microrheological response of athermal granular suspensions with and without hydrodynamic interactions to an externally driven probe particle by numerical simulations. We find that the presence of the fluid drastically increases the drag coefficient of the probe particle by more than one order of magnitude near the jamming transition. We reveal that this is a consequence of the nontrivial long-range nature of hydrodynamic interactions, which originates from unlimited cumulative transmission of near-field hydrodynamic interactions due to the incompressibility of both fluid and solid particles. Force chain formation of solid particles is dynamically coupled with hydrodynamic flow, leading to strong spatiotemporal fluctuations of flow pattern and nonlinear rheological response. Our study reveals essential roles of hydrodynamic interactions in complex rheological behavior of dense granular suspensions under an external drive.

Predicting Perceptual Decisions Using Visual Cortical Population Responses and Choice History.

Our understanding of the neural basis of perceptual decision making has been built in part on relating co-fluctuations of single neuron responses to perceptual decisions on a trial-by-trial basis. The strength of this relationship is often compared across neurons or brain areas, recorded in different sessions, animals, or variants of a task. We sought to extend our understanding of perceptual decision making in three ways. First, we measured neuronal activity simultaneously in early [primary visual cortex (V1)] and midlevel (V4) visual cortex while macaque monkeys performed a fine orientation discrimination perceptual task. This allowed a direct comparison of choice signals in these two areas, including their dynamics. Second, we asked how our ability to predict animals' decisions would be improved by considering small simultaneously-recorded neuronal populations rather than individual units. Finally, we asked whether predictions would be improved by taking into account the animals' choice and reward histories, which can strongly influence decision making. We found that responses of individual V4 neurons were weakly predictive of decisions, but only in a brief epoch between stimulus offset and the indication of choice. In V1, few neurons showed significant decision-related activity. Analysis of neuronal population responses revealed robust choice-related information in V4 and substantially weaker signals in V1. Including choice- and reward-history information improved performance further, particularly when the recorded populations contained little decision-related information. Our work shows the power of using neuronal populations and decision history when relating neuronal responses to the perceptual decisions they are thought to underlie.SIGNIFICANCE STATEMENT Decades of research has provided a rich description of how visual information is represented in the visual cortex. Yet how cortical responses relate to visual perception remains poorly understood. Here we relate fluctuations in small neuronal population responses, recorded simultaneously in primary visual cortex (V1) and area V4 of monkeys, to perceptual reports in an orientation discrimination task. Choice-related signals were robust in V4, particularly late in the behavioral trial, but not in V1. Models that include both neuronal responses and choice-history information were able to predict a substantial portion of decisions. Our work shows the power of integrating information across neurons and including decision history in relating neuronal responses to perceptual decisions.

Impact of Hanging Motionless in Harness on Respiratory and Blood Pressure Reflex Modulation in Mountain Climbers.

Harness hang syncope (HHS) is a risk that specifically affects safety of harness users in mountain climbing.Aims: To evaluate individual patterns of breathing resulting from deranged cardiovascular reflexes triggering a syncopal event when a mismatch between cerebral O2 demand and supply is present.Results: Forty healthy participants [aged 39.1 (8.2) years] were enrolled in a motionless suspension test while hanging in harness. Respiratory gas exchange values were analyzed to assess the pattern of breathing (EpInWel, respiratory elastic power) and cardiovascular parameters were monitored (BP, blood pressure). Four participants experienced HHS after 30.0 (7.6) minutes, with an early manifestation of loss of control of both a sustainable EpInWel and BP, starting after 10–12 minutes. Among the other participants, two different reactions were observed during suspension: (1) group G1 tolerated 32.7 (11.4) minutes of suspension by a favorable adaptation of the EpInWel and BP parameters and (2) group G2 showed significantly shorter time of suspension 24.0 (10.4) minutes with unfavorable increase in EpInWel and BP.Conclusions: Greater resistance to HHS occurs in people developing less marked fluctuations of both respiratory and cardiovascular reflex responses. Conversely, wider fluctuations both in control of EpInWel and BP were observed in the event of decreased suspension tolerance or in syncopal events.