Research on abnormal object detection in specific region based on Mask R-CNN

As an information carrier with rich semantics, image plays an increasingly important role in real-time monitoring of logistics management. Abnormal objects are typically closely related to the specific region. Detecting abnormal objects in the specific region is conducive to improving the accuracy of detection and analysis, thereby improving the level of logistics management. Motivated by these observations, we design the method called abnormal object detection in a specific region based on Mask R-convolutional neural network: Abnormal Object Detection in Specific Region. In this method, the initial instance segmentation model is obtained by the traditional Mask R-convolutional neural network method, then the region overlap of the specific region is calculated and the overlapping ratio of each instance is determined, and these two parts of information are fused to predict the exceptional object. Finally, the abnormal object is restored and detected in the original image. Experimental results demonstrate that our proposed Abnormal Object Detection in Specific Region can effectively identify abnormal objects in a specific region and significantly outperforms the state-of-the-art methods.

Ionizing the intergalactic medium by star clusters: the first empirical evidence

ABSTRACT We present a VLT/X-Shooter spectroscopy of the Lyman continuum (LyC) emitting galaxy Ion2 at z = 3.2121 and compare it to that of the recently discovered strongly lensed LyC emitter at z = 2.37, known as the Sunburst arc. Three main results emerge from the X-Shooter spectrum: (a) the Ly α has three distinct peaks with the central one at the systemic redshift, indicating a ionized tunnel through which both Ly α and LyC radiation escape; (b) the large O32 oxygen index ([O iii] λλ4959, 5007/[O ii] λλ3727, 3729) of $9.18_{-1.32}^{+1.82}$ is compatible to those measured in local (z ∼0.4) LyC leakers; (c) there are narrow nebular high-ionization metal lines with σv < 20 km s−1, which confirms the presence of young hot, massive stars. The He iiλ1640 appears broad, consistent with a young stellar component including Wolf–Rayet stars. Similarly, the Sunburst LyC emitter shows a triple-peaked Ly α profile and from VLT/MUSE spectroscopy the presence of spectral features arising from young hot and massive stars. The strong lensing magnification, (μ > 20), suggests that this exceptional object is a gravitationally bound star cluster observed at a cosmological distance, with a stellar mass M ≲ 107 M⊙ and an effective radius smaller than 20 pc. Intriguingly, sources like Sunburst but without lensing magnification might appear as Ion2-like galaxies, in which unresolved massive star clusters dominate the ultraviolet emission. This work supports the idea that dense young star clusters can contribute to the ionization of the IGM through holes created by stellar feedback.

Contributions of Micro-comparative Research to Language Documentation

This chapter discusses the symbiotic relationship of linguistic description and comparative research. Linguistic typology relies on detailed studies of individual languages, and grammatical description of endangered and non-endangered languages benefits from prior and concurrent study of closely related languages and the identification of parameters of similarity and difference. This view is supported by discussion of phenomena in Bantu languages, including tone and reduplication with considerable micro-parametric variation, particularly involving object markers. Two case studies are presented: (i) exceptional tonal properties of the first person singular object prefix N- and the reflexive marker di-i- in Yao, and (ii) exceptional patterns of reduplication involving /i/-initial verbs in Buguumbe Kuria which suggest a connection with the reflexive. Knowledge of analogous patterns in other languages informs the description and analysis of each language, and each case expands knowledge of the typology of patterns of exceptional object marking in Bantu languages, aiding future description of other languages.

K-theoretic exceptional collections at roots of unity

Using cyclotomic specializations of equivariant K-theory with respect to a torus action we derive congruences for discrete invariants of exceptional objects in derived categories of coherent sheaves on a class of varieties that includes Grassmannians and smooth quadrics. For example, we prove that if , where the ni's are powers of a fixed prime number p, then the rank of an exceptional object on X is congruent to ±1 modulo p.

236 years ago. . .

Some of the problems related to Near Earth Objects (NEOs), like orbit determination and ephemeris computation, are not new, and had to be dealt with since the beginning of NEO astronomy. The latter practically started with the discovery of Comet D/1770 L1 Lexell, that passed very close to the Earth in 1770; studies of the chaotic dynamics of this exceptional object continued well into the XIXth century. At the end of the XXth century there has been a renewal of interest in NEOs, as attested by IAU Symposium 236.

A Photoionization Model Study of NGC 7027

The physical characteristics of NGC7027 and the nature of the observations available make it an exceptional object to check the ability of steady photoionization modelling to correctly predict the emission spectrum of nebulae. After a decade of atomic physics and observation improvements, a complete updating of the analysis performed by Pequignot et al (1978) (Astron. Astrophys. 63, 313) is in order.