Quantity and quality of motor exploration are proposed to be fundamental for infant motor development. However, it is still not clear what types of motor exploration contribute to learning. To ...determine whether changes in quantity of leg movement and/or variability of leg acceleration are related to performance in a contingency learning task, twenty 6–8-month-old infants with typical development participated in a contingency learning task. During this task, a robot provided reinforcement when the infant’s right leg peak acceleration was above an individualized threshold. The correlation coefficient between the infant’s performance and the change in quantity of right leg movement, linear variability, and nonlinear variability of right leg movement acceleration from baseline were calculated. Simple linear regression and multiple linear regression were calculated to explain the contribution of each variable to the performance individually and collectively. We found significant correlation between the performance and the change in quantity of right leg movement (r = 0.86, p < 0.001), linear variability (r = 0.71, p < 0.001), and nonlinear variability (r = 0.62, p = 0.004) of right leg movement acceleration, respectively. However, multiple linear regression showed that only quantity and linear variability of leg movements were significant predicting factors for the performance ratio (p < 0.001, adjusted R2 = 0.94). These results indicated that the quantity of exploration and variable exploratory strategies could be critical for the motor learning process during infancy.
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•Infant’s performance in a contingency task is correlated with quantity of movement.•Infant’s performance is correlated with linear and nonlinear variability of movement.•Linear variability had a stronger effect than nonlinear variability in this task.•Quantity and variability of exploration could be critical for the motor learning.
Early interventions have the potential to positively influence infant movement patterns and support optimal neurodevelopmental outcomes. This work developed and validated a noncontact, socially ...assistive infant-robot interaction system that aimed to use contingent reward learning and imitation to deliver effective early interventions that complement human-delivered therapy.
Learning movement control is a fundamental process integral to infant development. However, it is still unclear how infants learn to control leg movement. This work explores the potential of using ...socially assistive robots to provide real-time adaptive reinforcement learning for infants. Ten 6 to 8-month old typically-developing infants participated in a study where a robot provided reinforcement when the infant's right leg acceleration fell within the range of 9 to 20 m/s 2 . If infants increased the proportion of leg accelerations in this band, they were categorized as "performers". Six of the ten participating infants were categorized as performers; the performer subgroup increased the magnitude of acceleration, proportion of target acceleration for right leg, and ratio of right/left leg acceleration peaks within the target acceleration band and their right legs increased movement intensity from the baseline to the contingency session. The results showed infants specifically adjusted their right leg acceleration in response to a robot- provided reward. Further study is needed to understand how to improve human-robot interaction policies for personalized interventions for young infants.
Context
. The Medium-Resolution Spectrometer (MRS) provides one of the four operating modes of the Mid-Infrared Instrument (MIRI) on board the
James Webb
Space Telescope (JWST). The MRS is an ...integral field spectrometer, measuring the spatial and spectral distributions of light across the 5–28 µm wavelength range with a spectral resolving power between 3700 and 1300.
Aims
. We present the MRS’s optical, spectral, and spectro-photometric performance, as achieved in flight, and we report on the effects that limit the instrument’s ultimate sensitivity.
Methods
. The MRS flight performance has been quantified using observations of stars, planetary nebulae, and planets in our Solar System. The precision and accuracy of this calibration was checked against celestial calibrators with well-known flux levels and spectral features.
Results
. We find that the MRS geometric calibration has a distortion solution accuracy relative to the commanded position of 8 mas at 5 µm and 23 mas at 28 µm. The wavelength calibration is accurate to within 9 km s
−1
at 5 µm and 27 km s
−1
at 28 µm. The uncertainty in the absolute spectro-photometric calibration accuracy was estimated at 5.6 ± 0.7%. The MIRI calibration pipeline is able to suppress the amplitude of spectral fringes to below 1.5% for both extended and point sources across the entire wavelength range. The MRS point spread function (PSF) is 60% broader than the diffraction limit along its long axis at 5 µm and is 15% broader at 28 µm.
Conclusions
. The MRS flight performance is found to be better than prelaunch expectations. The MRS is one of the most subscribed observing modes of JWST and is yielding many high-profile publications. It is currently humanity’s most powerful instrument for measuring the mid-infrared spectra of celestial sources and is expected to continue as such for many years to come.
The blue compact dwarf (BCD) galaxy I Zw 18 is one of the most metal-poor ($Z 3<!PCT!> \ sun $) star-forming galaxies known in the local Universe. Since its discovery, the evolutionary status of this ...system has been at the center of numerous debates within the astronomical community. We aim to probe and resolve the stellar populations of I Zw 18 in the near-IR using JWST/NIRCam's unprecedented imaging spatial resolution and sensitivity. Additionally, our goal is to derive the spatially resolved star formation history (SFH) of the galaxy within the last $1$ Gyr, and to provide constraints for older epochs. We used the point spread function fitting photometry package DOLPHOT to measure positions and fluxes of point sources in the $F115W$ and $F200W$ filters' images of I Zw 18, acquired as part of the JWST GTO ID 1233 (PI: Meixner). Furthermore, to derive I Zw 18's SFH, we applied a state-of-the-art color-magnitude diagram (CMD) fitting technique ( SFERA 2.0), using two independent sets of stellar models: PARSEC-COLIBRI and MIST. Our analysis of I Zw 18's CMD reveal three main stellar populations: one younger than $ Myr, mainly associated with the northwest star-forming (SF) region; an intermediate-age population ($ 100 - 800$ Myr), associated with the southeast SF region; and a red and faint population, linked to the underlying halo of the galaxy, older than $1$ Gyr and possibly as old as $13.8$ Gyr. The main body of the galaxy shows a very low star formation rate (SFR) of $ odot yr $ between $1$ and $13.8$ Gyr ago. In the last billion years, I Zw 18 shows an increasing trend, culminating in two strong bursts of SF around $ 10$ and $ Myr ago. Notably, I Zw 18 Component C mimics the evolution of the main body, but with lower SFRs on average. Our results confirm that I Zw 18 is populated by stars of all ages, without any major gaps. Thus, I Zw 18 is not a truly young galaxy, but rather a system characterized by an old underlying stellar halo, in agreement with what has been found in other BCDs by similar studies. The low SF activity exhibited at epochs older than $1$ Gyr is in agreement with the ``slow cooking’’ dwarf scenario proposed in the literature, and could have contributed to its low metal content. The galaxy is now experiencing its strongest episode of star formation ($ sun $) mainly located in the northwest region. A recent gravitational interaction between the main body and Component C is the most likely explanation for this starburst.
Exploratory movements during infancy help typically developing infants learn the connections between their own actions and desired outcomes. In contrast, infants who are at risk for developmental ...delays often have neuromotor impairments that negatively influence their motivation for movement. The goal of this work is to expand our understanding of infant responses to non-contact interactions with a small humanoid robot. In the initial work presented here, we focus on understanding how this type of robotic system might help to encourage typically developing infant motor exploration. A data collection with N=9 infants compared infant reactions to four robot conditions: saying "yay" with arm movement, saying "kick" with leg movement, saying "yay" with no movement, and saying "kick" with no movement. The results indicate that infants visually gazed at the robot while it moved, looking specifically to the part of the robot that was moving. Infants tended to move more during periods of robot inactivity. When the robot was moving, the infants also seemed more alert. Overall, these results can inform future studies of how to develop interventions to encourage movement practice by typically developing and at-risk infants.
The blue compact dwarf galaxy I Zw 18 is one of the most metal-poor (\(Z \sim 3% Z_{\sun}\)) star-forming galaxies in the local Universe. Its evolutionary status has sparked debate within the ...astronomical community. We aim to investigate the stellar populations of I Zw 18 in the near-IR using JWST/NIRCam's high spatial resolution and sensitivity. Additionally, we aim to derive the galaxy's spatially resolved star formation history (SFH) over the last 1 Gyr and provide constraints for older epochs. We used DOLPHOT to measure positions and fluxes of point sources in the F115W and F200W filters' images of I Zw 18. To derive I Zw 18's SFH, we applied the color-magnitude diagram (CMD) fitting technique SFERA 2.0, using two independent sets of stellar models. Our analysis reveals three main stellar populations: one younger than \(\sim30\) Myr, mainly in the northwest star-forming (SF) region; an intermediate-age population (\(\sim 100 - 800\) Myr) in the southeast SF region; and a red and faint population linked to the underlying halo, older than 1 Gyr and possibly as old as 13.8 Gyr. The main body of the galaxy shows a very low star formation rate (SFR) of \(\sim 10^{-4} M_{\odot} \text{yr}^{-1}\) between 1 and 13.8 Gyr ago. In the last billion years, I Zw 18 shows increasing SF, with strong bursts around \(\sim10\) and \(\sim100\) Myr ago. Component C mirrors the main body's evolution but with lower SFRs. Our findings confirm that I Zw 18 contains stars of all ages, indicating it is not a young galaxy but has an old stellar halo, similar to other BCDs. The low SF activity over the past billion years supports the "slow cooking" dwarf scenario, explaining its low metal content. Currently, the galaxy is undergoing its strongest SF episode (\(\sim 0.6 M_{\odot} \text{yr}^{-1}\)) mainly in the northwest region, likely due to a recent gravitational interaction with Component C.
The Medium-Resolution Spectrometer (MRS) provides one of the four operating modes of the Mid-Infrared Instrument (MIRI) on board the James Webb Space Telescope (JWST). The MRS is an integral field ...spectrometer, measuring the spatial and spectral distributions of light across the 5-28 \(\mu m\) wavelength range with a spectral resolving power between 3700-1300. We present the MRS's optical, spectral, and spectro-photometric performance, as achieved in flight, and we report on the effects that limit the instrument's ultimate sensitivity. The MRS flight performance has been quantified using observations of stars, planetary nebulae, and planets in our Solar System. The precision and accuracy of this calibration was checked against celestial calibrators with well-known flux levels and spectral features. We find that the MRS geometric calibration has a distortion solution accuracy relative to the commanded position of 8 mas at 5 \(\mu m\) and 23 mas at 28 \(\mu m\). The wavelength calibration is accurate to within 9 km/sec at 5 \(\mu m\) and 27 km/sec at 28 \(\mu m\). The uncertainty in the absolute spectro-photometric calibration accuracy was estimated at 5.6 +- 0.7 %. The MIRI calibration pipeline is able to suppress the amplitude of spectral fringes to below 1.5 % for both extended and point sources across the entire wavelength range. The MRS point spread function (PSF) is 60 % broader than the diffraction limit along its long axis at 5 \(\mu m\) and is 15 % broader at 28 \(\mu m\). The MRS flight performance is found to be better than prelaunch expectations. The MRS is one of the most subscribed observing modes of JWST and is yielding many high-profile publications. It is currently humanity's most powerful instrument for measuring the mid-infrared spectra of celestial sources and is expected to continue as such for many years to come.
Although electronic cigarettes (e-cigarettes) may help some smokers quit, some young adult never-smokers are now using e-cigarettes recreationally, potentially increasing their risk for initiation of ...smoking. We aimed to determine the association between baseline e-cigarette use and subsequent initiation of cigarette smoking among initially never-smoking young adults.
We conducted a prospective cohort study with assessments at baseline (March 2013) and follow-up (October 2014). We used sampling frames representing 97% of the US population to recruit a nationally representative sample of never-smoking young adults aged 18 to 30 years. The independent variable was baseline ever use of e-cigarettes. The main outcome measure was initiation of traditional cigarette smoking between baseline and 18-month follow-up.
Baseline surveys were completed by 1506 never-smoking young adults, of whom 915 (60.8%) completed follow-up. There were no demographic differences between responders and nonresponders. After applying survey weights—which accounted for both nonresponse and overcoverage or undercoverage—2.5% of the represented population of never-smokers (801,010 of 32,040,393) used e-cigarettes at baseline. Cigarette smoking was initiated by 47.7% of e-cigarette users and 10.2% of nonusers (P = .001). In fully adjusted multivariable models, e-cigarette use at baseline was independently associated with initiation of smoking at 18 months (adjusted odds ratio, 6.8; 95% confidence interval, 1.7-28.3). Results remained similar in magnitude and statistically significant in all sensitivity analyses.
Baseline e-cigarette use was independently associated with initiation of traditional cigarette smoking at 18 months. This finding supports policy and educational interventions designed to decrease use of e-cigarettes among nonsmokers.
Abstract Our understanding of how exoplanets form and evolve relies on analyses of both the mineralogy of protoplanetary disks and their detailed structures; however, these key complementary aspects ...of disks are usually studied separately. We present initial results from a hybrid model that combines the empirical characterization of the mineralogy of a disk, as determined from its mid-infrared spectral features, with the MCFOST radiative transfer disk model, a combination we call the Empirical and Radiative Transfer Hybrid (EaRTH) Disk Model. With the results of the mineralogy detection serving as input to the radiative transfer model, we generate mid-infrared spectral energy distributions (SEDs) that reflect both the mineralogical and structural parameters of the corresponding disk. Initial fits of the SED output by the resulting integrated model of Spitzer Space Telescope mid-infrared spectra of the protoplanetary disk orbiting the nearby T Tauri star MP Mus demonstrate the potential advantages of this approach by revealing details like the dominance of micron-sized olivine and micron-sized forsterite in this dusty disk. The simultaneous insight into disk composition and structure provided by the EaRTH Disk methodology should be directly applicable to the interpretation of mid-infrared spectra of protoplanetary disks that will be produced by the James Webb Space Telescope.
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