Search

Suzanne E Mazzeo,1,2 Madison Weinstock,1 Taylor Nadine Vashro,1,* Taryn Henning,1,* Karly Derrigo1 1Department of Psychology, Virginia Commonwealth University, Richmond, VA, USA; 2Department of Pediatrics, Virginia Commonwealth University, Richmond, VA, USA*These authors contributed equally to this workCorrespondence: Suzanne E Mazzeo, Virginia Commonwealth University, 806 W. Franklin St, 842018, Richmond, VA, 23284-2018, USA, Email semazzeo@vcu.eduAbstract: Social media has negative effects on adolescent body image and disordered eating behaviors, yet adolescents are unlikely to discontinue engaging with these platforms. Thus, it is important to identify strategies that can reduce the harms of social media on adolescent mental health. This article reviews research on social media and adolescent body image, and discusses strategies to reduce risks associated with social media use. Topics covered include interventions aimed at mitigating social media’s negative impacts, the body-positivity movement, and policies regulating adolescents’ social media use. Overall, this review highlights specific factors (such as staffing, duration, modality, facilitator training, and cultural sensitivity) to consider when designing and implementing social media interventions targeting adolescents. This review also discusses psychosocial outcomes associated with body positivity on social media. Finally, policy efforts to reduce the negative impact of social media on adolescents’ body image and eating behaviors are described. In sum, there is a strong need to conduct further research identifying optimal approaches to reduce the harms of social media for adolescent body image and eating behavior.Keywords: social media, body image, eating disorders, adolescent, review

Abstract After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and kinetic energy release distributions produced from an ensemble of internally excited 1-CNN+ studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence – radiative relaxation via thermally populated electronic excited states – efficiently stabilizes 1-CNN+, owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.

High-precision measurements are useful to find isotopic shifts and electron correlation. Here the authors measure electron affinity and hyperfine splitting of atomic oxygen with higher precision than previous studies.

We have studied the stability of C _59 anions as a function of time, from their formation on femtosecond timescales to their stabilization on second timescales and beyond, using a combination of theory and experiments. The ${{\rm{C}}}_{59}^{-}$ fragments were produced in collisions between C _60 fullerene anions and neutral helium gas at a velocity of 90 km s ^−1 (corresponding to a collision energy of 166 eV in the center-of-mass frame). The fragments were then stored in a cryogenic ion beam storage ring at the DESIREE facility, where they were followed for up to 1 minute. Classical molecular dynamics simulations were used to determine the reaction cross section and the excitation energy distributions of the products formed in these collisions. We find that about 15% of the ${{\rm{C}}}_{59}^{-}$ ions initially stored in the ring are intact after about 100 ms and that this population then remains intact indefinitely. This means that C _60 fullerenes exposed to energetic atoms and ions, such as stellar winds and shock waves, will produce stable, highly reactive products, like C _59 , that are fed into interstellar chemical reaction networks.

Abstract The tumor suppressor p53 is thought to play a key role in the maintenance of cell size and homeostasis, but relatively little is known about its role in skeletal muscle. Based on its ability to suppress cell growth, we hypothesized that inhibiting the function of wild-type p53 through the overexpression of a dominant-negative p53 mutant (DDp53) could result in muscle fiber hypertrophy. To test this hypothesis, we electroporated adult rat tibialis anterior muscles with DDp53 and collected the tissue three weeks later. We confirmed successful overexpression of DDp53 on a histological and biochemical level and found pronounced changes to muscle architecture, metabolism, and molecular signaling. Muscle mass, fiber cross-sectional area, and fiber diameter significantly decreased with DDp53 overexpression. We found histopathological changes in DDp53 transfected muscle which were accompanied by increased levels of proteins that are associated with membrane damage and repair. In addition, DDp53 decreased oxidative phosphorylation complex I and V protein levels, and despite its negative effects on muscle mass and fiber size, caused an increase in muscle protein synthesis as assessed via the SUnSET technique. Interestingly, the increase in muscle protein synthesis was concomitant with a decrease in phospho-S6K1 (Thr389). Furthermore, the muscle wasting in the DDp53 electroporated leg was accompanied by a decrease in global protein ubiquitination and an increase in proteasome activity. In conclusion, overexpression of a dominant-negative p53 mutant in skeletal muscle results in decreased muscle mass, myofiber size, histological muscle damage, a metabolic phenotype, and perturbed homeostasis between muscle protein synthesis and degradation.

Abstract The molecular responses to acute resistance exercise are well characterized. However, how cellular signals change over time to modulate chronic adaptations to more prolonged exercise training is less well understood. We investigated anabolic signaling and muscle protein synthesis rates at several time points after acute and chronic eccentric loading. Adult rat tibialis anterior muscle was stimulated for six sets of ten repetitions, and the muscle was collected at 0 h, 6 h, 18 h and 48 h. In the last group of animals, 48 h after the first exercise bout a second bout was conducted, and the muscle was collected 6 h later (54 h total). In a second experiment, rats were exposed to four exercise sessions over the course of 2 weeks. Anabolic signaling increased robustly 6 h after the first bout returning to baseline between 18 and 48 h. Interestingly, 6 h after the second bout mTORC1 activity was significantly lower than following the first bout. In the chronically exercised rats, we found baseline anabolic signaling was decreased, whereas myofibrillar protein synthesis (MPS) was substantially increased, 48 h after the last bout of exercise. The increase in MPS occurred in the absence of changes to muscle fiber size or mass. In conclusion, we find that anabolic signaling is already diminished after the second bout of acute resistance type exercise. Further, chronic exposure to resistance type exercise training results in decreased basal anabolic signaling but increased overall MPS rates.

Ion storage rings allow reactions to be studied over orders of magnitude in time, bridging the gap between typical experimental and astronomical timescales. Here the authors observe that polycyclic aromatic hydrocarbon fragments produced upon collision with He atoms at velocities typical of stellar winds and supernova shockwaves remain intact up to second timescales, thus may play an important role in interstellar chemistry.

Abstract Background Desminopathy is a clinically heterogeneous muscle disease caused by over 60 different mutations in desmin. The most common mutation with a clinical phenotype in humans is an exchange of arginine to proline at position 350 of desmin leading to p.R350P. We created the first CRISPR‐Cas9 engineered rat model for a muscle disease by mirroring the R350P mutation in humans. Methods Using CRISPR‐Cas9 technology, Des c.1045‐1046 (AGG > CCG) was introduced into exon 6 of the rat genome causing p.R349P. The genotype of each animal was confirmed via quantitative PCR. Six male rats with a mutation in desmin (n = 6) between the age of 120–150 days and an equal number of wild type littermates (n = 6) were used for experiments. Maximal plantar flexion force was measured in vivo and combined with the collection of muscle weights, immunoblotting, and histological analysis. In addition to the baseline phenotyping, we performed a synergist ablation study in the same animals. Results We found a difference in the number of central nuclei between desmin mutants (1 ± 0.4%) and wild type littermates (0.2 ± 0.1%; P

By repeatedly probing the a^{1}Δ excited state and the X^{3}Σ^{−} ground-state populations in a beam of CH^{−} ions stored in a cryogenic ion-beam storage ring for 100 s, we extract an intrinsic lifetime of 14.9±0.5 s for this excited state. This is far longer than all earlier experimental and theoretical results, exposing large difficulties in measuring and calculating slow decays and the need for benchmark quality experiments.

Abstract The mechanisms accounting for the loss of muscle function with obesity and type 2 diabetes are likely the result of a combination of neural and muscular factors. One muscular factor that is important, yet has received little attention, is the protein machinery involved in longitudinal and lateral force transmission. The purpose of this study was to compare the levels of force transfer and membrane integrity proteins before and after a 12‐week endurance training program in lean, obese, and obese type 2 diabetic adults. Nineteen sedentary subjects (male = 8 and female = 11) were divided into three groups: Lean (n = 7; 50.3 ± 4.1 y; 69.1 ± 7.2 kg); Obese (n = 6; 49.8 ± 4.1 y; 92.9 ± 19.5 kg); and Obese with type 2 diabetes (n = 6; 51.5 ± 7.9 years; 88.9 ± 15.1 kg). Participants trained 150 min/week between 55% and 75% of VO2max for 12 weeks. Skeletal muscle biopsies were taken before and after the training intervention. Baseline dystrophin and muscle LIM protein levels were higher (~50% p

Muscle loss is a severe complication of many medical conditions such as cancer, cardiac failure, muscular dystrophies, and nerve damage. The contribution of myofibrillar protein synthesis (MPS) to the loss of muscle mass after nerve damage is not clear. Using deuterium oxide (D2O) labeling, we demonstrate that MPS is significantly increased in rat m.tibialis anterior (TA) compared to control (3.23 ± 0.72 [damaged] to 2.09 ± 0.26%∗day−1 [control]) after 4 weeks of nerve constriction injury. This is the case despite substantial loss of mass of the TA (350 ± 96 mg [damaged] to 946 ± 361 mg [control]). We also show that expression of regulatory proteins involved with MPS (p70s6k1: 2.4 ± 0.3 AU [damaged] to 1.8 ± 0.2 AU [control]) and muscle protein breakdown (MPB) (MAFbx: 5.3 ± 1.2 AU [damaged] to 1.4 ± 0.4 AU [control]) are increased in nerve damaged muscle. Furthermore, the expression of p70s6k1 correlates with MPS rates (r2 = 0.57). In conclusion, this study shows that severe muscle wasting following nerve damage is accompanied by increased as opposed to decreased MPS.

Purpose. In an attempt to identify clinical and histopathological factors of prognostic importance in chondrosarcomas, 115 cases of malignant and borderline chondromatous tumours were reviewed.

Combined results are now available from a 15 year long search for Jupiter analogues around solar-type stars using the ESO CAT + CES, ESO 3.6 m + CES, and ESO 3.6 m + HARPS instruments. They comprise planet (co-)discoveries (ι Hor and HR 506) and confirmations (three planets in HR 3259) as well as non-confirmations of planets (HR 4523 and ɛ Eri) announced elsewhere. A long-term trend in ɛ Ind found by our survey is probably attributable to a Jovian planet with a period >30 yr, but we cannot fully exclude stellar activity effects as the cause. A 3.8 year periodic variation in HR 8323 can be attributed to stellar activity.

The ESPRI consortium will conduct an astrometric survey for extrasolar planets, using the PRIMA facility at the Very Large Telescope Interferometer. Our scientific goals include determining orbital inclinations and masses for planets already known from radial-velocity surveys, searches for planets around nearby stars of all masses, and around young stars. The consortium has built the PRIMA differential delay lines, developed an astrometric operation and calibration plan, and will deliver astrometric data reduction software.

We present preliminary single field results on a search for transiting extrasolar planets with the LAIWO wide field optical CCD camera, attached to the 1-m telescope at the Wise Observatory. With a 3 min integration time, the system achieved a few mmag precision for the brightest stars in a field of view of one square degree. We detect several periodic variables and a few transit-like events. The promising candidates will be followed-up in the near future.

Naphthalene and azulene are isomeric polycyclic aromatic hydrocarbons (PAHs) and are topical in the context of astrochemistry due to the recent discovery of substituted naphthalenes in the Taurus Molecular Cloud-1 (TMC-1). Here, the thermal- and photo-induced isomerization, dissociation, and radiative cooling dynamics of energized (vibrationally hot) naphthalene (Np+) and azulene (Az+) radical cations, occurring over the microsecond to seconds timescale, are investigated using a cryogenic electrostatic ion storage ring, affording "molecular cloud in a box" conditions. Measurement of the cooling dynamics and kinetic energy release distributions for neutrals formed through dissociation, until several seconds after hot ion formation, are consistent with the establishment of a rapid (sub-microsecond) Np+ ⇌ Az+ quasi-equilibrium. Consequently, dissociation by C2H2-elimination proceeds predominantly through common Az+ decomposition pathways. Simulation of the isomerization, dissociation, recurrent fluorescence, and infrared cooling dynamics using a coupled master equation combined with high-level potential energy surface calculations [CCSD(T)/cc-pVTZ], reproduce the trends in the measurements. The data show that radiative cooling via recurrent fluorescence, predominately through the Np+ D0 ← D2 transition, efficiently quenches dissociation for vibrational energies up to ≈1 eV above dissociation thresholds. Our measurements support the suggestion that small cations, such as naphthalene, may be more abundant in space than previously thought. The strategy presented in this work could be extended to fingerprint the cooling dynamics of other PAH ions for which isomerization is predicted to precede dissociation. [ABSTRACT FROM AUTHOR]

Absorption lines from exoplanet atmospheres observed in transmission allow us to study atmospheric characteristics such as winds. We present a new high-resolution transit time-series of HD 189733b, acquired with the PEPSI instrument at the LBT and analyse the transmission spectrum around the Na  d lines. We model the spectral signature of the RM-CLV-effect using synthetic PHOENIX spectra based on spherical LTE atmospheric models. We find an Na  d absorption signature between the second and third contact but not during the ingress and egress phases, which casts doubt on the planetary origin of the signal. Presupposing a planetary origin of the signal, the results suggest a weak day-to-nightside streaming wind in the order of 0.7 km s−1 and a moderate super-rotational streaming wind in the order of 3–4 km s−1, challenging claims of prevailing strong winds on HD 189733b. [ABSTRACT FROM AUTHOR]

Time-dependent photodetachment action spectra for the linear hydrocarbon anions C4H− and C6H− are investigated using the cryogenic Double ElectroStatic Ion Ring ExpEriment. The radiative cooling characteristics of these ions on the millisecond to seconds timescale are characterized by monitoring changes in their spectra as the ions cool by spontaneous infrared (IR) emission. The average cooling rates, extracted using Non-negative Matrix Factorization, are fit with 1/e lifetimes of 19 ± 2 and 3.0 ± 0.2 s for C4H− and C6H−, respectively. The cooling rates are successfully reproduced using a simple harmonic cascade model of IR emission. The ultraslow radiative cooling dynamics determined in this work provide important data for understanding the thermal cooling properties of linear hydrocarbon anions and for refining models of the formation and destruction mechanisms of these anions in astrochemical environments. [ABSTRACT FROM AUTHOR]

We have studied the stability of C59 anions as a function of time, from their formation on femtosecond timescales to their stabilization on second timescales and beyond, using a combination of theory and experiments. The C 59 − fragments were produced in collisions between C60 fullerene anions and neutral helium gas at a velocity of 90 km s−1 (corresponding to a collision energy of 166 eV in the center-of-mass frame). The fragments were then stored in a cryogenic ion beam storage ring at the DESIREE facility, where they were followed for up to 1 minute. Classical molecular dynamics simulations were used to determine the reaction cross section and the excitation energy distributions of the products formed in these collisions. We find that about 15% of the C 59 − ions initially stored in the ring are intact after about 100 ms and that this population then remains intact indefinitely. This means that C60 fullerenes exposed to energetic atoms and ions, such as stellar winds and shock waves, will produce stable, highly reactive products, like C59, that are fed into interstellar chemical reaction networks. [ABSTRACT FROM AUTHOR]

Context. The past few years have seen a revolution in the study of circumstellar disks. New instrumentation in the near-infrared and (sub)millimeter regimes have allowed us to routinely spatially resolve disks around young stars of nearby star-forming regions. As a result, we have found that substructures with scales of ~10 au in disks are common. We have also revealed a zoo of different morphologies, sizes, and luminosities that is as complex as the diversity of architectures found in evolved exoplanet systems. Aims. We study disk evolutionary trends as they appear in scattered light observations. Scattered light traces the micron-sized particles at the disk surface that are well coupled to the gas. This means that scattered light observations can be used to trace the distribution of the disk gas and its interaction with embedded perturbers. Methods. We used VLT/SPHERE to observe 20 systems in the Cha I cloud in polarized scattered light in the near-infrared. We combined the scattered light observations with existing literature data on stellar properties and with archival ALMA continuum data to study trends with system age and dust mass. We also connected resolved near-infrared observations with the spectral energy distributions of the systems. Results. In 13 of the 20 systems included in this study we detected resolved scattered light signals from circumstellar dust. For the CR Cha, CT Cha, CV Cha, SY Cha, SZ Cha, and VZ Cha systems we present the first detailed descriptions of the disks in scattered light. The observations found typically smooth or faint disks, often with little substructure, with the notable exceptions of SZ Cha, which shows an extended multiple-ringed disk, and WW Cha, which shows interaction with the cloud environment. New high S/N K-band observations of the HD 97048 system in our survey reveal a significant brightness asymmetry that may point to disk misalignment and subsequent shadowing of outer disk regions, possibly related to the suggested planet candidate in the disk. We resolve for the first time the stellar binary in the CS Cha system. Multiple wavelength observations of the disk around CS Cha have revealed that the system contains small, compact dust grains that may be strongly settled, consistent with numerical studies of circumbinary disks. We find in our sample that there is a strong anti-correlation between the presence of a (close) stellar companion and the detection of circumstellar material with five of our seven nondetections located in binary systems. We also find a correlation between disk mass, as inferred from millimeter observations, and the detection of scattered light signal. Finally, we find a tentative correlation between relative disk-to-star brightness in scattered light and the presence of a dust cavity in the inner (unresolved) disk, as traced by the system spectral energy distribution. At the same time, faint disks in our sample are generally younger than 2 Myr. [ABSTRACT FROM AUTHOR]

Context. Space-based mid-infrared (IR) spectroscopy is a powerful tool for the characterization of important star formation tracers of warm gas which are unobservable from the ground. The previous mid-IR spectra of bright high-mass protostars with the Infrared Space Observatory (ISO) in the hot-core phase typically show strong absorption features from molecules such as CO2, C2H2, and HCN. However, little is known about their fainter counterparts at earlier stages. Aims. We aim to characterize the gas-phase molecular features in James Webb Space Telescope Mid-Infrared Instrument Medium Resolution Spectrometer (MIRI/MRS) spectra of the young and clustered high-mass star-forming region IRAS 23385+6053. Methods. Spectra were extracted from several locations in the MIRI/MRS field of view, targeting two mid-IR sources tracing embedded massive protostars as well as three H2 bright outflow knots at distances of >8000 au from the multiple. Molecular features in the spectra were fit with local thermodynamic equilibrium (LTE) slab models, with their caveats discussed in detail. Results. Rich molecular spectra with emission from CO, H2, HD, H2O, C2H2, HCN, CO2, and OH are detected towards the two mid-IR sources. However, only CO and OH are seen towards the brightest H2 knot positions, suggesting that the majority of the observed species are associated with disks or hot core regions rather than outflows or shocks. The LTE model fits to 12CO2, C2H2, HCN emission suggest warm 120–200 K emission arising from a disk surface around one or both protostars. The abundances of CO2 and C2H2 of ~10−7 are consistent with previous observations of high-mass protostars. Weak ~500 K H2O emission at ~6–7 µm is detected towards one mid-IR source, whereas 250–1050 K H2O absorption is found in the other. The H2O absorption may occur in the disk atmosphere due to strong accretion-heating of the midplane, or in a disk wind viewed at an ideal angle for absorption. CO emission may originate in the hot inner disk or outflow shocks, but NIRSpec data covering the 4.6 µm band head are required to determine the physical conditions of the CO gas, as the high temperatures seen in the MIRI data may be due to optical depth. OH emission is detected towards both mid-IR source positions and one of the shocks, and is likely excited by water photodissociation or chemical formation pumping in a highly non-LTE manner. Conclusions. The observed molecular spectra are consistent with disks having already formed around two protostars in the young IRAS 23385+6054 system. Molecular features mostly appear in emission from a variety of species, in contrast to the more evolved hot core phase protostars which typically show only absorption; however, further observations of young high-mass protostars are needed to disentangle geometry and viewing angle effects from evolution. [ABSTRACT FROM AUTHOR]

Spontaneous and photo-induced decay processes of HfF5− and WF5− molecular anions were investigated in the Double ElectroStatic Ion Ring ExpEriment (DESIREE). The observation of these reactions over long time scales (several tens of ms) was possible due to the cryogenic temperatures (13 K) and the extremely low residual gas pressure (∼10−14 mbar) of DESIREE. For photo-induced reactions, laser wavelengths in the range 240 to 450 nm were employed. Both anion species were found to undergo spontaneous decay via electron detachment or fragmentation. After some ms, radiative cooling processes were observed to lower the probability for further decay through these processes. Photo-induced reactions indicate the existence of an energy threshold for WF5− anions at about 3.5 eV, above which the neutralization yield increases strongly. By contrast, HfF5− ions exhibit essentially no enhanced production of neutrals upon photon interaction, even for the highest photon energy used in this experiment (∼5.2 eV). This suppression will be highly beneficial for the efficient detection, in accelerator mass spectrometry, of the extremely rare isotope 182Hf using the 182HfF5− anion while effectively reducing the interfering stable isobar 182W in the analyte ion 182WF5−. The radionuclide 182Hf is of great relevance in astrophysical environments as it constitutes a potential candidate to study the events of nucleosynthesis that may have taken place in the vicinity of the solar system several million years ago. [ABSTRACT FROM AUTHOR]