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The Meaning in Life Questionnaire (MLQ) is a popular tool to measure the presence of and one’s search for meaning in life. Although the validity of the MLQ has been verified in previous studies, the evidence from longitudinal measurement invariance (LMI) of the MLQ is still lacking. The current study aimed to examine the LMI of the MLQ in a sample of Chinese college students (N = 328) at a 1-year interval. Multigroup confirmatory factor analysis (MCFA) was used to examine the LMI of the MLQ over four time points (over the course of 1 year). Results indicate that the MLQ has strict longitudinal invariance across 1-year in Chinese college students, and the latent means difference of MLQ-P is not significant differences across time, while the latent means difference of MLQ-S show significant differences between Time 1 and the other time points. Moreover, the internal consistency reliabilities (e.g., alpha and omega) of the MLQ scores were acceptable at all four time points, and the stability coefficients across time were moderate. These findings provide preliminary evidence that the MLQ has satisfactory longitudinal properties in Chinese college students.

This study explored the molecular mechanism behind the protective effects from low-dose lipopolysaccharide (LPS) on an in-vitro model of spinal cord injury (SCI). For this, PC12 cells were treated with different concentrations of LPS and the cell counting kit-8 assay was used to measure the toxicity of LPS to the cells. Next, we used immunofluorescence to measure nuclear translocation of Nrf2 in PC12 cells. PC12 cells were then treated with IGF-1 (PI3K agonist) and LY294002 (PI3K inhibitor). An in-vitro model of SCI was then established via oxygen--glucose deprivation/reoxygenation. Rates of apoptosis were measured using flow cytometry and the TUNEL assay. Low-dose LPS increased the expression levels of Nrf2, p-PI3K/PI3K, and p-AKT/AKT, and facilitated nuclear translocation of Nrf2. The activation of PI3K--AKT signaling by IGF-1 significantly increased the expression of Nrf2, whereas inhibition of PI3K--AKT signaling significantly decreased the expression of Nrf2. Low-dose LPS reduced the apoptotic ratio of PC12 cells, decreased the expression levels of caspase 3 and caspase 9, and increased the expression levels of HO-1, NQO1, and [gamma]-GCS. Low-dose LPS also reduced the rate of apoptosis and oxidative stress by activating the PI3K--AKT--Nrf2 signaling pathway. Collectively, the results indicate that PI3K--AKT--Nrf2 signaling participates in the protective effects from low-dose LPS in an in-vitro PC12 cell model of SCI. Key words: low-dose lipopolysaccharide, nerve cells, spinal cord injury, PI3K--AKT--Nrf2 signaling. L'étude visait à explorer le mécanisme moléculaire potentiel de l'effet protecteur d'une faible dose de lipopolysac-charide (LPS) dans un modèle in vitro de lésion de la moelle épinière (LME). Dans un premier temps, des cellules PC12 ont été traitées avec différentes concentrations de LPS et le test CCK-8 a été utilisé pour détecter la toxicité cellulaire du LPS. Puis, la translocation nucléaire de Nrf2 dans les cellules PC12 a été déterminée par immunofluorescence. Les cellules PC12 ont ensuite été traitées avec l'IGF-1 (agoniste de la PI3K) et le LY294002 (inhibiteur de la PI3K). Un modèle in vitro de LME a ensuite été établi par privation d'oxygène--glucose et réoxygénation. L'apoptose a été détectée par cytométrie de flux et par le test TUNEL. Le LPS à faible dose accroissait l'expression de Nrf2, p-PI3K/PI3K et p-AKT/AKT, et facilitait la translocation nucléaire de Nrf2. L'activation de la signalisation PI3K/AKT par l'IGF-1 augmentait de manière significative l'expression de Nrf2, alors que l'inhibition de la signalisation PI3K--AKT diminuait remarquablement l'expression de Nrf2. Le LPS à faible dose réduisait le rapport des cellules PC12 en apoptose, diminuait l'expression de la caspase 3 et de la caspase 9, et augmentait l'expression de HO-1, NQO1 et [gamma]-GCS. Parallèlement, le LPS à faible dose atténuait l'apoptose et le stress oxydant en activant la signalisation PI3K--AKT--Nrf2. En somme, la signalisation PI3K--AKT--Nrf2 participe à la protection par le LPS à faible dose dans un modèle in vitro de LME constitué des cellules PC12. [Traduit par la Rédaction] Mots-clés : lipopolysaccharide à faible dose, cellules nerveuses, lésions de la moelle épinière, signalisation PI3K--AKT--Nrf2., Introduction Spinal cord injury (SCI) is a serious trauma to the central nervous system with high disability rate in orthopedics (Luo et al. 2018). According to a recent report, there [...]

The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst (GRB)–like models, thus revealing their progenitors and physical mechanisms. In this work, we systematically study the MVTs of hundreds of X-ray bursts (XRBs) from SGR J1935+2154 observed by Insight-HXMT, GECAM, and Fermi/Gamma-ray Burst Monitor from 2014 July to 2022 January through the Bayesian block algorithm. We find that the MVTs peak at ∼2 ms, corresponding to a light-travel time size of about 600 km, which supports the magnetospheric origin in pulsar-like models. The shock radius and the Lorentz factor of the jet are also constrained in GRB-like models. Interestingly, the MVT of the XRB associated with FRB 200428 is ∼70 ms, which is longer than that of most bursts and implies its special radiation mechanism. In addition, the median of MVTs is 7 ms, shorter than the median MVTs of 40 ms and 480 ms for short GRBs or long GRBs, respectively. However, the MVT is independent of duration, similar to GRBs. Finally, we investigate the energy dependence of MVT and suggest that there is a marginal evidence for a power-law relationship like GRBs, but the rate of variation is at least about an order of magnitude smaller. These features may provide an approach to identify bursts with a magnetar origin.

We have performed a spectral-timing analysis of the black hole X-ray binary MAXI J1535-571 during its 2017 outburst, with the aim of exploring the evolution of the inner accretion flow geometry. X-ray reverberation lags are observed in the hard-intermediate state (HIMS) and soft-intermediate state of the outburst. During the HIMS, the characteristic frequency of the reverberation lags ν _0 (the frequency at which the soft lag turns to zero in lag–frequency spectra) increases when the spectrum softens. This reflects a reduction of the spatial distance between the corona and accretion disk, when assuming the measured time lags are associated with the light travel time. We also find a strong correlation between ν _0 and the type-C quasi-periodic oscillation (QPO) centroid frequency ν _QPO , which can be well explained by the Lense–Thirring precession model under a truncated disk geometry. Despite the degeneracy in the spectral modeling, our results suggest that the accretion disk is largely truncated in the low hard state, and moves inward as the spectrum softens. Combine the spectral modeling results with the ν _0 – ν _QPO evolution, we are inclined to believe that this source probably has a truncated disk geometry in the hard state.

The determination of the absolute and relative position of a spacecraft is critical for its operation, observations, data analysis, scientific studies, as well as deep-space exploration in general. A spacecraft that can determine its own absolute position autonomously may perform better than those that must rely on transmission solutions. In this work, we report an absolute navigation accuracy of ∼20 km using 16 day Crab pulsar data observed with Fermi’s Gamma-ray Burst Monitor (GBM). In addition, we propose a new method with the inverse process of the triangulation for joint navigation using repeated bursts like those from the magnetar SGR J1935+2154 observed by the Gravitational-wave High-energy Electromagnetic Counterpart All-sky Monitor and GBM.

The first X-ray source catalog of the Insight-HXMT Galactic Plane (∣ b ∣ < 10°) Scanning Survey (GPSS) is presented based on the data accumulated from 2017 June to 2021 August. The 4 yr limit sensitivities at main energy bands can reach 8.2 × 10 ^−12 erg s ^−1 cm ^2 (2−6 keV), 4.21 × 10 ^−11 erg s ^−1 cm ^2 (7−40 keV), and 2.78 × 10 ^−11 erg s ^−1 cm ^2 (25−100 keV). More than 1300 sources have been monitored at a wide band (1−100 keV), of which 223 sources have a signal-to-noise ratio greater than 5. We combined the GPSS data of Insight-HXMT and MAXI and found it feasible to obtain more complete long-term light curves from their scanning results. The flux variabilities at different energy bands of the 223 bright sources are analyzed based on the excess variances. It is found that the fluxes of X-ray binaries are more active than those of supernova remnants and isolated pulsars. Different types of binaries, e.g., low-mass X-ray binaries (LMXBs), high-mass X-ray binaries (HMXBs), neutron star binaries, and black hole binaries, also distinctively show different regularities. In addition, the relations between the hardness ratio (HR) and excess variances, and HR and source types are analyzed. It is obvious that the HRs of HMXBs tend to be harder than those of LMXBs and HMXBs tend to be more active than those of LMXBs.