Research of the active reflector antenna using laser angle metrology system

Active reflector is one of the key technologies for constructing large telescopes, especially for the millimeter/sub-millimeter radio telescopes. This article introduces a new efficient laser angle metrology system for the active reflector antenna of the large radio telescopes, with a plenty of active reflector experiments mainly about the detecting precisions and the maintaining of the surface shape in real time, on the 65-meter radio telescope prototype constructed by Nanjing Institute of Astronomical Optics and Technology (NIAOT). The test results indicate that the accuracy of the surface shape segmenting and maintaining is up to micron dimension, and the time-response can be of the order of minutes. Therefore, it is proved to be workable for the sub-millimeter radio telescopes.Comment: 10 pages, 15 figure

Application of prenatal ultrasonography and magnetic resonance imaging on fetal agenesis of corpus callosum

Objectives: To evaluate the diagnostic value and clinical application of prenatal ultrasonography (US) and Magnetic Resonance Imaging (MRI) for different types of fetal Agenesis of the Corpus Callosum (ACC). Material and methods: There were 42 cases of fetal ACC discovered by routine US, including complete ACC 18 cases and partial ACC 24 cases, checked by MRI within 1 week. The results were confirmed by head ultrasound after birth or brain biopsy after labor induction. Results: From prenatal ultrasonic diagnosis, 18 cases were complete ACC and 24 cases were partial ACC. MRI was able to find complete ACC in 11 cases, partial ACC in 16 cases, and non-ACC in 15 cases. Labor induction or birth confirmed that, 11 cases were complete ACC, 14 cases were partial ACC, and 17 cases were non-ACC.The results of different types of ACC were detected by ultrasound and MRI were statistically significant (p < 0.05).MRI examination was superior to ultrasound in specificity, positive predictive value, negative predictive value, Youden index, and diagnostic index. Conclusions: MRI is high specific degrees, diagnostic performance is satisfactory, should be use as a necessary method for prenatal definitive diagnosis of ACC. However, prenatal ultrasound can be tested repeatedly and can be combined with blood flow imaging detection in real time, and it is still the preferred method for screening fetal structural malformation in a comprehensive way, which is suitable for general screening of ACC

(Naphthalene-2,3-diolato-κ2 O,O′)[tris­(2-pyridyl­meth­yl)amine-κ4 N]cobalt(III) hexa­fluoridophosphate hemihydrate

In the title complex, [Co(C10H6O2)(C18H18N4)]PF6·0.5H2O, the CoIII ion is six-coordinated in a distorted octa­hedral geometry by four N atoms from a tris­(2-pyridyl­meth­yl)amine ligand and two O atoms from a naphthalene-2,3-diolate ligand. The asymmetric unit contains two complex cations, two hexa­fluoridophosphate anions and one uncoordinated water mol­ecule. In one of the hexa­fluoridophosphate anions, four of the F aroms are disordered over two sets of sites in a 0.632 (11):0.368 (11) ratio. In the crystal, the cations, anions and water mol­ecules are connected by O—H⋯O and O—H⋯F hydrogen bonds. π–π inter­actions are present between the pyridine rings [centroid–centroid distance = 3.814 (1) Å]

Role of Nrf2 in bone metabolism

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor expressed in many cell types, including osteoblasts, osteocytes, and osteoclasts. Nrf2 has been considered a master regulator of cytoprotective genes against oxidative and chemical insults. The lack of Nrf2 can induce pathologies in multiple organs. Nrf2 deficiency promotes osteoclast differentiation and osteoclast activity, which leads to an increase in bone resorption. The role of Nrf2 in osteoblast differentiation and osteoblast activity is more complex. Nrf2 mediates anabolic effects within an ideal range. Nrf2 deletion suppresses load induced bone formation and delays fracture healing. Overall, Nrf2 plays an important role in the regulation of bone homeostasis in bone cells

Characteristics of gamma-ray burst afterglows in the context of non-axisymmetric structured jets

As the most energetic explosions in the Universe, gamma-ray bursts (GRBs) are commonly believed to be generated by relativistic jets. Recent observational evidence suggests that the jets producing GRBs are likely to have a structured nature. Some studies have suggested that non-axisymmetric structured jets may be formed through internal non-uniform magnetic dissipation processes or the precession of the central engine. In this study, we analyze the potential characteristics of GRB afterglows within the framework of non-axisymmetric structured jets. We simplify the profile of the asymmetric jet as a step function of the azimuth angle, dividing the entire jet into individual elements. By considering specific cases, we demonstrate that the velocity, energy, and line-of-sight direction of each jet element can greatly affect the behaviour of the overall light curve. The radiative contributions from multiple elements may lead to the appearance of multiple distinct peaks or plateaus in the light curve. Furthermore, fluctuations in the rising and declining segments of each peak can be observed. These findings establish a theoretical foundation for future investigations into the structural characteristics of GRBs by leveraging GRB afterglow data.Comment: Monthly Notices of the Royal Astronomical Society, Volume 525, Issue 4, November 2023, Pages 6285-629