3,6-Dimethyl-N 1,N 4-bis­(pyridin-2-yl)-1,2,4,5-tetra­zine-1,4-dicarboxamide

In the title mol­ecule, C16H16N8O2, four atoms of the tetra­zine ring are coplanar, with the largest deviation from the plane being 0.0236 (12) Å; the other two atoms of the tetra­zine ring deviate on the same side from this plane by 0.320 (4) and 0.335 (4) Å. Therefore, the central tetra­zine ring exhibits a boat conformation. The dihedral angles between the mean plane of the four coplanar atoms of the tetrazine ring and the two pyridine rings are 26.22 (10) and 6.97 (5)°. The two pyridine rings form a dihedral angle of 31.27 (8)°. In the molecule, there are a number of short C—H⋯O interactions. In the crystal, molecules are linked via a C—H⋯O interaction to form zigzag chains propagating along the [010] direction

Holmes: An Efficient and Lightweight Semantic Based Anomalous Email Detector

Email threat is a serious issue for enterprise security, which consists of various malicious scenarios, such as phishing, fraud, blackmail and malvertisement. Traditional anti-spam gateway commonly requires to maintain a greylist to filter out unexpected emails based on suspicious vocabularies existed in the mail subject and content. However, the signature-based approach cannot effectively discover novel and unknown suspicious emails that utilize various hot topics at present, such as COVID-19 and US election. To address the problem, in this paper, we present Holmes, an efficient and lightweight semantic based engine for anomalous email detection. Holmes can convert each event log of email to a sentence through word embedding then extract interesting items among them by novelty detection. Based on our observations, we claim that, in an enterprise environment, there is a stable relation between senders and receivers, but suspicious emails are commonly from unusual sources, which can be detected through the rareness selection. We evaluate the performance of Holmes in a real-world enterprise environment, in which it sends and receives around 5,000 emails each day. As a result, Holmes can achieve a high detection rate (output around 200 suspicious emails per day) and maintain a low false alarm rate for anomaly detection

Challenges and Opportunities in Parent-Teacher Relationships in Contemporary China

This study explores how market economy affects parent-teacher relationships in China. Guided by Bourdieu’s (1986) capital theory, we interviewed twenty-one teachers and twenty parents in China. The study reveals that the market economy has impacted changes in parent-teacher relationships in several aspects. First, modern technology such as the Internet and WeChat has facilitated communication between parents and teachers with fast pace and convenience. Moreover, the study makes an original contribution to the field by challenging stereotyping assumptions towards Chinese parents who are either completely not involved or partially involved in their child’s education at home. The study shows that contemporary Chinese parents are actively involved in their children’s education both at home and at school. Furthermore, the market economy has shaken the high social status that teachers enjoyed in the past. As a result, parents prefer to adopt pragmatic approaches to parent-teacher relationships. Finally, the urban, middle-class parents whose social capital, alongside cultural, symbolic and economic capital enable them to mobilize their social networks in interacting with the school. They appear to be more likely than previous generations of Chinese parents to challenge teachers’ authority, and there have been more serious conflicts between parents and teachers. The study focuses on China, but these rare insights highlight current and emerging dangers to parent-teacher engagement with relevance to many other countries

Pentaquark states with the QQQqqˉQQQq\bar{q} configuration in a simple model

We discuss the mass splittings for the $S$-wave triply heavy pentaquark states with the $QQQq\bar{q}$ $(Q=b,c;q=u,d,s)$ configuration which is a mirror structure of $Q\bar{Q}qqq$. The latter configuration is related with the nature of $P_c(4380)$ observed by the LHCb Collaboration. The considered pentaquark masses are roughly estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. $\Xi_{cc}D$, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons.Comment: 19 pages, 1 figure, 10 tables; Version accepted by Eur. Phys. J.