NGTS and HST insights into the long-period modulation in GW Librae

Light curves of the accreting white dwarf pulsator GW Librae spanning a 7.5-month period in 2017 were obtained as part of the Next-Generation Transit Survey. This data set comprises 787 h of photometry from 148 clear nights, allowing the behaviour of the long (hours) and short-period (20 min) modulation signals to be tracked from night to night over a much longer observing baseline than has been previously achieved. The long-period modulations intermittently detected in previous observations of GW Lib are found to be a persistent feature, evolving between states with periods ≃ 83 min and 2–4 h on time-scales of several days. The 20 min signal is found to have a broadly stable amplitude and frequency for the duration of the campaign, but the previously noted phase instability is confirmed. Ultraviolet observations obtained with the Cosmic Origin Spectrograph on-board the Hubble Space Telescope constrain the ultraviolet-to-optical flux ratio to ≃5 for the 4 h modulation, and ≲1 for the 20 min period, with caveats introduced by non-simultaneous observations. These results add further observational evidence that these enigmatic signals must originate from the white dwarf, highlighting our continued gap in theoretical understanding of the mechanisms that drive them

Three Short Period Jupiters from TESS

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V=11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 +/- 0.078 Mjup planet in a grazing transit configuration with an impact parameter of b = 1.17 +0.10/-0.08. As a result the radius is poorly constrained, 2.03 +0.61/-0.49 Rjup. The planet's distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Qs' = 10^7 - 10^9. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 +/- 0.13 Mjup and a radius of 1.29 +/- 0.02 Rjup. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V=12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V=12.4 G-type star. It has a mass of 0.79 +/- 0.06 Mjup and a radius of 1.09 +0.08/-0.05 Rjup. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe/H] ranging from 0.18 - 0.24.Comment: Published in A&

Three Short Period Jupiters from TESS. HIP 65Ab, TOI-157b and TOI-169b

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 M_J planet in a grazing transit configuration with an impact parameter of b = 1.17_(−0.08)^(+0.10). As a result the radius is poorly constrained, 2.03_(−0.49)^(+0.61)R_J. The planet’s distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Qs′ = 10⁷ − 10⁹. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13 M_J and a radius of 1.29 ± 0.02 R_J. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06 M_J and a radius of 1.09_(−0.05)^(+0.08)R_J. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to 0.24

Automated postural responses are modified in a functional manner by instruction.

Contains fulltext : 70025.pdf (publisher's version ) (Open Access)The restoration of upright balance after a perturbation relies on highly automated and, to a large extent, stereotyped postural responses. Although these responses occur before voluntary control comes into play, previous research has shown that they can be functionally modulated on the basis of cognitive set (experience, advanced warning, instruction, etc.). It is still unknown, however, how the central nervous system deals with situations in which the postural response is not necessarily helpful in the execution of a task. In the present study, the effects of instruction on automated postural responses in neck, trunk, shoulder, and leg muscles were investigated when people were either instructed to recover balance after being released from an inclined standing posture [balance recovery (BR) trials], or not to recover at all and fall onto a safety mattress in the most comfortable way [fall (F) trials], in both backward and leftward directions. Participants were highly successful in following the instructions, consistently exhibiting stepping responses for balance recovery in BR trials, and suppressing stepping in the F trials. Yet EMG recordings revealed similar postural responses with onset latencies between 70 and 130 ms in both BR and F trials, with slightly delayed responses in F trials. In contrast, very pronounced and early differences were observed between BR and F trials in response amplitudes, which were generally much higher in BR than in F trials, but with clear differentiation between muscles and perturbation directions. These results indicate that a balance perturbation always elicits a postural response, irrespective of the task demands. However, when a specific balance recovery response is not desired after a perturbation, postural responses can be selectively downregulated and integrated into the motor output in a functional and goal-oriented way

NGTS and HST insights into the long period modulation in GW Librae

Light curves of the accreting white dwarf pulsator GW Librae spanning a 7.5 month period in 2017 were obtained as part of the Next Generation Transit Survey. This data set comprises 787 hours of photometry from 148 clear nights, allowing the behaviour of the long (hours) and short period (20min) modulation signals to be tracked from night to night over a much longer observing baseline than has been previously achieved. The long period modulations intermittently detected in previous observations of GW Lib are found to be a persistent feature, evolving between states with periods ~83min and 2-4h on time-scales of several days. The 20min signal is found to have a broadly stable amplitude and frequency for the duration of the campaign, but the previously noted phase instability is confirmed. Ultraviolet observations obtained with the Cosmic Origin Spectrograph onboard the Hubble Space Telescope constrain the ultraviolet-to-optical flux ratio to ~5 for the 4h modulation, and <=1 for the 20min period, with caveats introduced by non-simultaneous observations. These results add further observational evidence that these enigmatic signals must originate from the white dwarf, highlighting our continued gap in theoretical understanding of the mechanisms that drive them

Trypanosoma cruzi: Maintenance in Culture Modify Gene and Antigenic Expression of Metacyclic Trypomastigotes

In this study we examined whether the maintenance of Trypanosoma cruzi by long-time in axenic culture produces changes in gene expression and antigenic profiles. The studies were made with a Dm30L-clone from a low-virulent strain and a non-cloned virulent EP-strain of T. cruzi. Both parasites were maintained, for at least seven years, by successive alternate passage triatomine/mouse (triatomine condition), or by serial passage in axenic medium (culture condition). The comparison of the [35S]methionine metabolic labeling products of virulent and non-virulent parasites by 2D-SDS-PAGE, clearly indicates that the expression of metacyclic trypomastigotes (but not of epimastigotes) proteins have been altered by laboratory maintenance conditions. Western blot analysis of EP and Dm30L-epimastigotes using a serum anti-epimastigotes revealed that although most of antigens are conserved, four antigens are characteristics of triatomine condition parasites and three other are characteristics of culture condition parasites. Anti-metacyclics serum revealed significative differences in EP- and Dm30L-metacyclic trypomastigotes from triatomine condition. However, avirulent metacyclic forms were antigenically very similar. These results suggest that besides a possible selection of avirulent subpopulation from T. cruzi strains genetically heterogeneous when maintained by long time in axenic culture, changes in virulence might be due to post-translational modifications of the antigens induced by the absence of the natural alternability (vertebrate-invertebrate) in the life-cycle of T. cruz