3,038 research outputs found
Skill-biased remote work and incentives
Full text linkWe document four key trends since the pandemic: a surge in remote work, an increase in performance pay, their joint occurrence, and the skill-biased nature of this complementarity. We develop a firm-worker model that explains this evidence. We show that, under risk aversion, the incentive-compatible performance pay premium falls with worker’s skills, as the likelihood of a good performance increases. Hence, the firm uses
performance pay if the worker is sufficiently skilled and fixed pay with monitoring, otherwise. The unforeseen pandemic shock forces the firm to adopt remote work and reduces monitoring effectiveness. As a result, the firm relies more on performance pay. Post-pandemic, the firm always sticks to the remote work if the worker is sufficiently skilled. If the worker is too unskilled for performance pay to be cost-effective, the firm sticks to remote work only if remote monitoring is effective. Accordingly, the model
redicts that a decline in remote monitoring efficacy could reduce remote work for less-skilled workers only
Influence of acquisition frame-rate and video compression techniques on pulse-rate variability estimation from vPPG signal
No full textIn this paper, common time- and frequency-domain variability indexes obtained by pulse rate variability (PRV) series extracted from video-photoplethysmographic signal (vPPG) were compared with heart rate variability (HRV) parameters calculated from synchronized ECG signals. The dual focus of this study was to analyze the effect of different video acquisition frame-rates starting from 60 frames-per-second (fps) down to 7.5 fps and different video compression techniques using both lossless and lossy codecs on PRV parameters estimation. Video recordings were acquired through an off-the-shelf GigE Sony XCG-C30C camera on 60 young, healthy subjects (age 23±4 years) in the supine position. A fully automated, signal extraction method based on the Kanade-Lucas-Tomasi (KLT) algorithm for regions of interest (ROI) detection and tracking, in combination with a zero-phase principal component analysis (ZCA) signal separation technique was employed to convert the video frames sequence to a pulsatile signal. The frame-rate degradation was simulated on video recordings by directly sub-sampling the ROI tracking and signal extraction modules, to correctly mimic videos recorded at a lower speed. The compression of the videos was configured to avoid any frame rejection caused by codec quality leveling, FFV1 codec was used for lossless compression and H.264 with variable quality parameter as lossy codec. The results showed that a reduced frame-rate leads to inaccurate tracking of ROIs, increased time-jitter in the signals dynamics and local peak displacements, which degrades the performances in all the PRV parameters. The root mean square of successive differences (RMSSD) and the proportion of successive differences greater than 50 ms (PNN50) indexes in time-domain and the low frequency (LF) and high frequency (HF) power in frequency domain were the parameters which highly degraded with frame-rate reduction. Such a degradation can be partially mitigated by up-sampling the measured signal at a higher frequency (namely 60 Hz). Concerning the video compression, the results showed that compression techniques are suitable for the storage of vPPG recordings, although lossless or intra-frame compression are to be preferred over inter-frame compression methods. FFV1 performances are very close to the uncompressed (UNC) version with less than 45% disk size. H.264 showed a degradation of the PRV estimation directly correlated with the increase of the compression ratio
Relationships between heart-rate variability and pulse-rate variability obtained from video-PPG signal using ZCA
Full text linkIn this paper, classical time and frequency-domain variability indexes obtained by pulse rate variability (PRV) series extracted from videophotoplethysmography signals (vPPG) were compared with heart rate variability (HRV) parameters extracted from ECG signals. The study focuses on the analysis of the changes observed during a rest-to-stand manoeuvre (a mild sympathetic stimulus) performed on 60 young, normal subjects (age: 24±3 years). The objective is to evaluate if video-derived PRV indexes may replace HRV in the assessment of autonomic responses to external stimulation. Video recordings were performed with a GigE Sony XCG-C30C camera and analyzed offline to extract the vPPG signal. A new method based on zero-phase component analysis (ZCA) was employed in combination with a fully-automatic method for detection and tracking of region of interest (ROI) located on the forehead, the cheek and the nose. Results show an overall agreement between time and frequency domain indexes computed on HRV and PRV series. However, some differences exist between resting and standing conditions. During rest, all the indexes computed on HRV and PRV series were not statistically significantly different (p > 0.05), and showed high correlation (Pearsons r > 0.90). The agreement decreases during standing, especially for the high-frequency, respirationrelated parameters such as RMSSD (r = 0.75), pNN50 (r = 0.68) and HF power (r = 0.76). Finally, the power in the LF band (n.u.) was observed to increase significantly during standing by both HRV (28±14 versus 45±16 (n.u.); rest versus standing) and PRV (26±12 versus 30±13(n.u.); rest versus standing) analysis, but such an increase was lower in PRV parameters than that observed by HRV indexes. These results provide evidence that some differences exist between variability indexes extracted from HRV and video-derived PRV, mainly in the HF band during standing. However, despite these differences video-derived PRV indexes were able to evince the autonomic responses expected by the sympathetic stimulation induced by the rest-to-stand manoeuvre
Assessment of beat-to-beat heart rate detection method using a camera as contactless sensor
No full textVideo photoplethysmography (videoPPG) has emerged as area of great interest thanks to the possibility of remotely assessment of cardiovascular parameters, as heart rate (HR), respiration rate (RR) and heart rate variability (HRV). The present article proposes a fully automated method based on chrominance model, that selects for each subject the best region of interest (ROI) to detect and evaluate the accuracy of beat detection and interbeat intervals (IBI) measurements. The experimental recordings were conducted on 26 subjects which underwent a rest-to-stand maneuver. The results show that the accuracy of beat detection is slightly better during supine position (95%) compared to the standing one (92%), due to the maintenance of the balance that introduces larger motion artifact in the signal dynamic. The error in the measurement (expressed as mean±sd) of instantaneous heart rate is of +0.04 ±3.29 bpm in rest and +0.01±4.26 bpm in stand
Reward from public office, and the selection of politicians by parties
Full text linkWe investigate the relationship between the quality of politicians, defined in terms of their competence (skills), and rewards from public office in a game between parties and citizens in which parties play a crucial role in the selection of politicians. Parties shape the selection of politicians by manipulating information about the quality of their candidates. An increase in the rewards from public offices leads to two opposing effects on the average quality of politicians. The first is a selection effect, whereby more skilled citizens enter politics, leading to an increase in average quality. The second is a manipulation effect, as parties have the incentive to further manipulate information so to increase the probability of election for their unskilled candidates, from whom they can extract higher rents in the form of service duties. We find that the second effect dominates when i. parties’ costs of manipulating information are sufficiently low; ii. even in the absence of manipulation, the quality of information available to citizens about candidates is sufficiently poor; and iii. the net gains from becoming a politician for unskilled citizens are sufficiently larger than those for skilled citizens. These findings provide a rationale for the ambiguous sign of the empirical relationship between the quality and pay of politicians
Do we need more time for leisure?
Full text link”We need more time: more time for leisure” Linton Kwesi Jonhson used to dub. Indeed, the analysis of an OLG economy with endogenous labor supply gives some rational to the dub poet’s claims. In our setting, the golden rule is defined as the pair of capital-labour ratio and individual labour supply which maximises the steady state utility of each generation. When, other things equal, agents are motivated to work more the higher the level of wages, individual labor supply will be increasing (decreasing) in capital labor ratio according to whether the elasticity of wages per unit of labour is bigger (smaller) than the relative change of the value of the fraction of labour income saved. Hence, if the economy is dynamically efficient, agents tend to work more than in the Golden Age if the propensity to save evaluated at the golden rule is, other things equal, relatively high. Conversely, under dynamic inefficiency, they work too much if and only if the propensity to save is relatively low. For given values of the parameters determining the propensity to save, individuals in dynamic efficient (inefficient) economies work more than in the Golden Age as long as the labour share of income is sufficiently high (low). These findings appear to be of some interest with reference to the 35 hours working-week debate in Europe
Analysis of Instantaneous Linear, Nonlinear and Complex Cardiovascular Dynamics from Videophotoplethysmography
No full textBACKGROUND: There is a fast growing interest in the use of non-contact devices for health and performance assessment in humans. In particular, the use of non-contact videophotoplethysmography (vPPG) has been recently demonstrated as a feasible way to extract cardiovascular information. Nevertheless, proper validation of vPPG-derived heartbeat dynamics is still missing.OBJECTIVE: We aim to an in-depth validation of time-varying, linear and nonlinear/complex dynamics of the pulse rate variability extracted from vPPG.METHODS: We apply inhomogeneous pointprocess nonlinear models to assess instantaneous measures defined in the time, frequency, and bispectral domains as estimated through vPPG and standard ECG. Instantaneous complexity measures, such as the instantaneous Lyapunov exponents and the recently defined inhomogeneous point-process approximate and sample entropy, were estimated as well. Video recordings were processed using our recently proposed method based on zerophase principal component analysis. Experimental data were gathered from 60 young healthy subjects (age: 24±3 years) undergoing postural changes (rest-to-stand maneuver).RESULTS: Group averaged results show that there is an overall agreement between linear and nonlinear/complexity indices computed from ECG and vPPG during resting state conditions. However, important differences are found, particularly in the bispectral and complexity domains, in recordings where the subjects has been instructed to stand up.CONCLUSIONS: Although significant differences exist between cardiovascular estimates from vPPG and ECG, it is very promising that instantaneous sympathovagal changes, as well as time-varying complex dynamics, were correctly identified, especially during resting state. In addition to a further improvement of the video signal quality, more research is advocated towards a more precise estimation of cardiovascular dynamics by a comprehensive nonlinear/complex paradigm specifically tailored to the non-contact quantification
Assessment of instantaneous cardiovascular dynamics from video plethysmography
No full textAlthough there is growing interest in estimating cardiovascular information using contactless video plethysmography (VP), an in-depth validation of time-varying, nonlinear dynamics of the related pulse rate variability is still missing. In this study we estimate the heartbeat through VP and standard ECG, and employ inhomogeneous point-process nonlinear models to assess instantaneous heart rate variability measures defined in the time, frequency, and bispectral domains. Experimental data were gathered from 60 young healthy subjects (age: 24±3 years) undergoing postural changes (rest-to-stand maneuver). Video recordings are processed using our recently proposed method based on zero-phase component analysis. Results show that, at a group level, there is an overall agreement between linear and nonlinear indices computed from ECG and VP during resting state conditions. However, significant differences are found, especially in the bispectral domain, when considering data gathered while standing. Although significant differences exist between cardiovascular estimates from VP and ECG, results can be considered very promising as instantaneous sympatho-vagal changes were correctly identified. More research is indeed needed to improve on the precise estimation of nonlinear sympatho-vagal interactions
Analysis of physiological and non-contact signals to evaluate the emotional component in consumer preferences
Full text linkEmotions are an essential drive in decision making and may influence consumer preference. In this study we assessed the influence of brands in product preference after tasting 2 soft-drinks (Coca Cola vs. Cola beverage), by using physiological measurements, namely the skin conductance, the respiratory rate and heart rate variability (HRV) extracted using contactless sensors. The experimental protocol enrolled twenty-five young subjects which were asked to taste 2 soft drinks in random order, without knowing the brand (blind condition) and then knowing the brand (not blind condition). After each phase the subject was asked to choose the preferred beverage. Our main hypothesis is that if the subject knows the brand there is an arousal effect, independently from the absolute appreciation of the product. In order to evaluate the emotional components, the skin conductance, respiratory and Video-Photoplethysmographic (PPG) signals were continuously recorded throughout the experiment. The Video-PPG was then processed to extract HRV parameters. We observed that the arousal levels changed among beverages and conditions, going from higher arousal for Coca-Cola in the blind condition, to higher arousal for Cola in the not blind condition. Moreover, 44% of the subjects changed their preference when the brand was uncovered: from blind to not blind conditions, 6 subjects went from Cola to Coca-Cola as preferred drink and 5 went from Coca-Cola to Cola. Opposite results were found for the two beverages when comparing the physiological response when the beverage was/was not preferred. Finally, differences were found also between consumers and not consumers of Coca-Cola and the blind/not blind comparison. We conclude that the brand is a fundamental element in a request for choice and it can affect the first emotional response of a subject
- …
